Dissertations / Theses on the topic 'N-type silicon'
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Porter, Nicholas Andrew. "Magnetoresistance in n-type silicon." Thesis, University of Leeds, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.534834.
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Chen, Wan Lam Florence Photovoltaics & Renewable Energy Engineering Faculty of Engineering UNSW. "PECVD silicon nitride for n-type silicon solar cells." Publisher:University of New South Wales. Photovoltaics & Renewable Energy Engineering, 2008. http://handle.unsw.edu.au/1959.4/41277.
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The cost of crystalline silicon solar cells must be reduced in order for photovoltaics to be widely accepted as an economically viable means of electricity generation and be used on a larger scale across the world. There are several ways to achieve cost reduction, such as using thinner silicon substrates, lowering the thermal budget of the processes, and improving the efficiency of solar cells. This thesis examines the use of plasma enhanced chemical vapour deposited silicon nitride to address the criteria of cost reduction for n-type crystalline silicon solar cells. It focuses on the surface passivation quality of silicon nitride on n-type silicon, and injection-level dependent lifetime data is used extensively in this thesis to evaluate the surface passivation quality of the silicon nitride films. The thesis covers several aspects, spanning from characterisation and modelling, to process development, to device integration. The thesis begins with a review on the advantages of using n-type silicon for solar cells applications, with some recent efficiency results on n-type silicon solar cells and a review on various interdigitated backside contact structures, and key results of surface passivation for n-type silicon solar cells. It then presents an analysis of the influence of various parasitic effects on lifetime data, highlighting how these parasitic effects could affect the results of experiments that use lifetime data extensively. A plasma enhanced chemical vapour deposition process for depositing silicon nitride films is developed to passivate both diffused and non-diffused surfaces for n-type silicon solar cells application. Photoluminescence imaging, lifetime measurements, and optical microscopy are used to assess the quality of the silicon nitride films. An open circuit voltage of 719 mV is measured on an n-type, 1 Ω.cm, FZ, voltage test structure that has direct passivation by silicon nitride. Dark saturation current densities of 5 to 15 fA/cm2 are achieved on SiN-passivated boron emitters that have sheet resistances ranging from 60 to 240 Ω/□ after thermal annealing. Using the process developed, a more profound study on surface passivation by silicon nitride is conducted, where the relationship between the surface passivation quality and the film composition is investigated. It is demonstrated that the silicon-nitrogen bond density is an important parameter to achieve good surface pas-sivation and thermal stability. With the developed process and deeper understanding on the surface passivation of silicon nitride, attempts of integrating the process into the fab-rication of all-SiN passivated n-type IBC solar cells and laser doped n-type IBC solar cells are presented. Some of the limitations, inter-relationships, requirements, and challenges of novel integration of SiN into these solar cell devices are identified. Finally, a novel metallisation scheme that takes advantages of the different etching and electroless plating properties of different PECVD SiN films is described, and a preliminary evalua-tion is presented. This metallisation scheme increases the metal finger width without increasing the metal contact area with the underlying silicon, and also enables optimal distance between point contacts for point contact solar cells. It is concluded in this thesis that plasma enhanced chemical vapour deposited silicon nitride is well-suited for n-type silicon solar cells.
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Scansen, Donald W. "Excess noise in n-type hydrogenated amorphous silicon." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq23898.pdf.
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Valavanis, Alexander. "n-type silicon-germanium based terahertz quantum cascade lasers." Thesis, University of Leeds, 2009. http://etheses.whiterose.ac.uk/1262/.
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Terahertz quantum cascade lasers (THz QCLs) have many potential applications, including detection of skin tumours, and of illicit drugs and explosives. To date, all THz QCLs use III–V compound semiconductors, but silicon (Si)-based devices could offer significant benefits. The high thermal conductivity of Si may allow higher operating temperatures, removing the need for large and costly cryogenic coolers, and the non-polar nature of Si may allow a wider range of emission frequencies. The mature Si processing technology may reduce fabrication costs and ultimately allow integration of THz QCLs with mainstream semiconductor electronics. This work investigates the suitability of a range of Si-based material configurations for THz QCL design. An effective mass/envelope function model of the electronic bandstructure is developed, taking into account the effects of strain and crystal orientation. Scattering models for Coulombic interactions, structural imperfections and interactions with phonons (lattice vibrations) are developed and used to predict the electron distribution, current density and gain in a range of device designs. The effect of nonabrupt interface geometries is investigated and the effect of intervalley mixing upon the emission spectrum is considered. It is shown that germanium/germanium–silicon heterostructures offer much better prospects for THz QCL development than silicon/silicon–germanium systems and can yield sufficient optical gain to overcome the threshold for copper–copper waveguides.
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Merazga, Amar. "Steady state and transient photoconductivity in n-type amorphous silicon." Thesis, University of Abertay Dundee, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277887.
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Edwards, Matthew Bruce ARC Centre of Excellence in Advanced Silicon Photovoltaics & Photonics Faculty of Engineering UNSW. "Screen and stencil print technologies for industrial N-type silicon solar cells." Publisher:University of New South Wales. ARC Centre of Excellence in Advanced Silicon Photovoltaics & Photonics, 2008. http://handle.unsw.edu.au/1959.4/41372.
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To ensure that photovoltaics contributes significantly to future world energy production, the cost per watt of producing solar cells needs to be drastically reduced. The use of n-type silicon wafers in conjunction with industrial print technology has the potential to lower the cost per watt of solar cells. The use of n-type silicon is expected to allow the use of cheaper Cz substrates, without a corresponding loss in device efficiency. Printed metallisation is well utilised by the PV industry due to its low cost, yet there are few examples of its application to n-type solar cells. This thesis explores the use of n-type Cz silicon with printed metallisation and diffusion from printed sources in creating industrially applicable solar cell structures. The thesis begins with an overview of existing n-type solar cell structures, previous printed thick film metallisation research and previous research into printed dopant sources. A study of printed thick-film metallisation for n-type solar cells is then presented, which details the fabrication of boron doped p-type emitters followed by a survey of thick film Ag, Al, and Ag/Al inks for making contact to a p-emitter layer. Drawbacks of the various inks include high contact resistance, low metal conductivity or both. A cofire regime for front and rear contacts is established and an optimal emitter selected. A study of printed dopant pastes is presented, with an objective to achieve selective, heavily doped regions under metal contacts without significantly compromising minority carrier lifetime in solar cells. It is found that heavily doped regions are achievable with both boron and phosphorus, but that only phosphorus paste was capable of post-processing lifetime compatible with good efficiencies. The effect of belt furnace processing on n-type silicon wafers is explored, with large losses in implied voltage observed due to contamination of Si wafers from transition metals present in the belt furnace. Due to exposure to chromium in the belt furnace, no significant advantage in using n-type wafers instead of p-type is observed during the belt furnace processing step. Finally, working solar cells with efficiencies up to 16.1% are fabricated utilising knowledge acquired in the earlier chapters. The solar cells are characterised using several new photoluminescence techniques, including photoluminescence with current extraction to measure the quality of metal contacts. The work in this thesis indicates that n-type printed silicon solar cell technology shows potential for good performance at low cost.
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Lam, Chi-hung, and 林志雄. "Defect study of N-type 6H silicon carbide using positron lifetime spectroscopy." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B29753260.
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Lam, Chi-hung. "Positron annihilation spectroscopy studies of 6H N-type silicon carbide and Zn-doped P-type gallium antimonide." Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B36299996.
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Ryu, Kyung Sun. "Development of low-cost and high-efficiency commercial size n-type silicon solar cells." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53842.
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The objective of the research in this thesis was to develop high-efficiency n-type silicon solar cells at low-cost to reach grid parity. This was accomplished by reducing the electrical and optical losses in solar cells through understanding of fundamental physics and loss mechanisms, development of process technologies, cell design, and modeling. All these technology enhancements provided a 3.44% absolute increase in efficiency over the 17.4% efficient n-type PERT solar cell. Finally, 20.84% efficient n-type PERT (passivated emitter and rear totally diffused) solar cells were achieved on commercial grade 239cm2 n-type Cz silicon wafers with optimized front boron emitter without boron-rich layer and phosphorus back surface field, silicon dioxide/silicon nitride stack for surface passivation, optimized front grid pattern with screen printed 5 busbars and 100 gridlines, and improved rear contact with laser opening and physical vapor deposition aluminum. This thesis also suggested research directions to improve cell efficiency further and attain ≥21% efficient n-type solar cells which involves three additional technology developments including the use of floating busbars, selective emitters, and negatively charged aluminum oxide (Al2O3) film for boron emitter surface passivation.
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Ho, King-fung, and 何競豐. "Some positron annihilation studies on highly doped and supersaturated N-type silicon." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B30287108.
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Ning, Steven. "Simulation and process development for ion-implanted N-type silicon solar cells." Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47684.
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As the efficiency potential for the industrial P-type Al-BSF silicon solar cell reaches its limit, new solar cell technologies are required to continue the pursuit of higher efficiency solar power at lower cost. It has been demonstrated in literature that among possible alternative solar cell structures, cells featuring a local BSF (LBSF) have demonstrated some of the highest efficiencies seen to date. Implementation of this technology in industry, however, has been limited due to the cost involved in implementing the photolithography procedures required. Recent advances in solar cell doping techniques, however, have identified ion implantation as a possible means of performing the patterned doping required without the need for photolithography.
In addition, past studies have examined the potential for building solar cells on N-type silicon substrates, as opposed to P-type. Among other advantages, it is possible to create N-type solar cells which do not suffer from the efficiency degradation under light exposure that boron-doped P-type solar cells are subject to. Industry has not been able to capitalize on this potential for improved solar cell efficiency, in part because the fabrication of an N-type solar cell requires additional masking and doping steps compared to the P-type solar cell process. Again, however, recent advances in ion implantation for solar cells have demonstrated the possibility for bypassing these process limitations, fabricating high efficiency N-type cells without any masking steps.
It is clear that there is potential for ion implantation to revolutionize solar cell manufacturing, but it is uncertain what absolute efficiency gains may be achieved by moving to such a process. In addition to development of a solar specific ion implant process, a number of new thermal processes must be developed as well. With so many parameters to optimize, it is highly beneficial to have an advanced simulation model which can describe the ion implant, thermal processes, and cell performance accurately. Toward this goal, the current study develops a process and device simulation model in the Sentaurus TCAD framework, and calibrates this model to experimentally measured cells. The study focuses on three main tasks in this regard:
Task I - Implant and Anneal Model Development and Validation
This study examines the literature in solar and microelectronics research to identify features of ion implant and anneal processes which are pertinent to solar cell processing. It is found that the Monte Carlo ion implant models used in IC fabrication optimization are applicable to solar cell manufacture, with adjustments made to accommodate for the fact that solar cell wafers are often pyramidally textured instead of polished. For modeling the thermal anneal processes required after ion implant, it is found that the boron and phosphorus cases need to be treated separately, with their own diffusion models.
In particular, boron anneal simulation requires accurate treatment of boron-interstitial clusters (BICs), transient enhanced diffusion, and dose loss. Phosphorus anneal simulation requires treatment of vacancy and interstitial mediated diffusion, as well as dose loss and segregation. The required models are implemented in the Sentaurus AdvancedModels package, which is used in this study. The simulation is compared to both results presented in literature and physical measurements obtained on wafers implanted at the UCEP. It is found that good experimental agreement may be obtained for sheet resistance simulations of implanted wafers, as well as simulations of boron doping profile shape. The doping profiles of phosphorus as measured by the ECV method, however, contain inconsistencies with measured sheet resistance values which are not explained by the model.
Task II - Device Simulation Development and Calibration
This study also develops a 3D model for simulation of an N-type LBSF solar cell structure. The 3D structure is parametrized in terms of LBSF dot width and pitch, and an algorithm is used to generate an LBSF structure mesh with this parametrization. Doping profiles generated by simulations in Task I are integrated into the solar cell structure. Boundary conditions and free electrical parameters are calibrated using data from similar solar cells fabricated at the UCEP, as well as data from lifetime test wafers. This simulation uses electrical models recommended in literature for solar cell simulation.
It is demonstrated that the 3D solar cell model developed for this study accurately reproduces the performance of an implanted N-type full BSF solar cell, and all parameters fall within ranges expected from theoretical calculations. The model is then used to explore the parameter space for implanted N-type local BSF solar cells, and to determine conditions for optimal solar cell performance. It is found that adding an LBSF to the otherwise unchanged baseline N-type cell structure can produce almost 1% absolute efficiency gain. An optimum LBSF dot pitch of 450um at a dot size of 100um was identified through simulation. The model also reveals that an LBSF structure can reduce the fill factor of the solar cell, but this effect can be offset by a gain in Voc. Further efficiency improvements may be realized by implementing a doping-dependent SRV model and by optimizing the implant dose and thermal anneal.
Task III - Development of a Procedure for Ion Implanted N-type LBSF Cell Fabrication
Finally, this study explores a method for fabrication of ion-implanted N-type LBSF solar cells which makes use of photolithographically defined nitride masks to perform local phosphorus implantation. The process utilizes implant, anneal, and metallization steps previously developed at the UCEP, as well as new implant masking steps developed in the course of this study. Although an LBSF solar cell has not been completely fabricated, the remaining steps of the process are successfully tested on implanted N-type full BSF solar cells, with efficiencies reaching 20.0%.
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Lam, Chi-hung, and 林志雄. "Positron annihilation spectroscopy studies of 6H N-type silicon carbide and Zn-doped P-type gallium antimonide." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B36299996.
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Frey, Alexander [Verfasser]. "Industrial n-Type Silicon Solar Cells with Co-Diffused Boron Emitters / Alexander Frey." Konstanz : Bibliothek der Universität Konstanz, 2018. http://d-nb.info/1161342966/34.
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Favre, Wilfried. "Silicium de type n pour cellules à hétérojonctions : caractérisations et modélisations." Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00635222.
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Les cellules à hétérojonctions de silicium fabriquées par croissance de couches minces de silicium amorphe hydrogéné (a-Si :H) à basse température sur des substrats de silicium cristallin (c-Si) peuvent atteindre des rendements de conversion photovoltaïque élevés (η=23 % démontré). Les efforts de recherche ayant principalement été orientés vers le cristallin de type p jusqu'à présent en France, ce travail s'attache à l'étude du type n pour d'une part déterminer les performances auxquelles s'attendre avec cette nouvelle filière et d'autre part les améliorer. Pour cela, nous avons mis en œuvre des techniques de caractérisation des matériaux composant la structure et de l'interface (a-Si :H/c-Si) couplées à des outils de simulations numériques afin mieux comprendre les phénomènes de transport électronique. Nous nous sommes également intéressés aux cellules à hétérojonctions avec substrats de silicium multicristallin de type n, le silicium multicristallin étant le matériau le plus répandu actuellement dans la fabrication des cellules photovoltaïques.
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Kramer, Illan. "Fabrication and characterization of a hybrid heterojunction composed of N-type silicon and PEDOT:PSS." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99774.
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A hybrid organic/inorganic heterojunction has been fabricated using an n-type silicon wafer (< 111 >, 3 < ρ < 6 Ω · cm) and a p-type polymer, PEDOT:PSS (ρ = 1 Ω · cm). Standard fabrication techniques such as vacuum deposition and spin coating are required for fabrication and have been employed. I-V characteristics have been measured under both dark and illuminated conditions for different thicknesses of PEDOT:PSS as defined by the spin rate at which the polymer has been spin coated. The data has been analyzed and figures of merit such as series resistance, short circuit current, open circuit voltage, fill factor and efficiency have been calculated. The efficiency ranges to values as high as 0.63%, while the fill factor has been observed to be as high as 57%, both of which are improvements on previously reported hybrid heterojunctions built on n-type silicon wafers.
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Heinz, Friedemann D., Matthias Breitwieser, Paul Gundel, Markus König, Matthias Hörteis, Wilhelm Warta, and Martin C. Schubert. "Microscopic origin of the aluminium assisted spiking effects in n-type silicon solar cells." Elsevier, 2014. https://publish.fid-move.qucosa.de/id/qucosa%3A72455.
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Contact formation with silver (Ag) thick film pastes on boron emitters of n-type crystalline silicon (Si) solar cells is a nontrivial technological task. Low contact resistances are up to present only achieved with the addition of aluminium (Al) to the paste. During contact formation, Al assisted spiking from the paste into the silicon emitter and bulk occurs, thus leading to a low contact resistance but also to a deterioration of other cell parameters. Both effects are coupled and can be adjusted by choosing proper Al contents of the paste and temperatures for contact formation. In this work the microscopic electric properties of single spikes are presented. These microscopic results, i.e. alterations of the local emitter doping density, the pronounced local recombination activity at the interface between spikes and Si and its influence on the charge collection efficiency, are used to explain the observed dependencies of global cell parameters on the Al content of contact pastes.
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Chiguluri, Praneeth. "Quasi-steady-state Photoluminescence Lifetime Imaging of p- and n-type Multicrystalline Silicon Wafers." Ohio University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1300311806.
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Walker, Zane Harry. "Kinetics of the reaction of intrinsic and N-type silicon with atomic and molecular bromine and chlorine." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/32378.
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The etching of silicon by atomic and molecular chlorine and bromine was studied as a function of etchant pressure and reaction temperature. Various types of silicon were employed in the etching experiments including intrinsic and n-type polycrystalline silicon as well as the (100) face of intrinsic single crystal silicon. The pressures of Cl₂ and Br₂ varied from 0.1 to 30 Torr and the partial pressure of Cl and Br atoms was between 0.08 and 0.2 Torr. Temperatures of between 365 and 600°C were required for CI₂ and Br₂ etching, while lower temperatures of 25 to 470°C were sufficient for the more reactive Cl and Br atoms.
The reaction between silicon and Br atoms was shown to be first order with respect to the partial pressure of atoms and a first order dependence was assumed for Cl atom etching. The rate constants were determined for the Cl and Br atom etching of intrinsic and n-type polycrystalline silicon, with a dopant concentration of 5x10¹⁸ atoms cm⁻³. The reactivity of Cl atoms with n-type silicon was approximately 90 times greater than with intrinsic silicon. This enhancement in reaction rate is primarily due to an increase in the preexponential factor in k₁, with the activation enthalpy for the process remaining unchanged at approximately 28 kJ mol⁻¹. For Br atom etching, the reaction rate for the n-type silicon was over 300 times greater than for intrinsic silicon and was characterized by activation enthalpies of 55 and 63 kJ mol⁻¹ respectively. The enhancement in reactivity can also be attributed principally to an increase in the preexponential factor. The preexponential factors for the rate constants are larger than those expected, based on the collision frequencies of Cl and Br atoms. This is interpreted as evidence for a preadsorption step in these reactions.
The reactions of silicon with CI₂ and Br₂ were found to display a complex pressure dependence. The etch rates varied linearly with (etchant pressure)¹′² and the intercepts from a linear regression of the data were slightly negative. To account for the half order pressure dependencies observed in these etching reactions, a reversible dissociative adsorption mechanism is proposed whereby Br₂ (or CI₂) is dissociatively adsorbed, in a reversible reaction, onto the silicon surface yielding two atoms bound to the surface. This step is then followed by a first order reaction leading to the formation of a species which is either gaseous product or some precursor which forms that product in a subsequent non rate-determining step.
From the slopes of etch rate versus (pressure)¹′² plots, composite half order rate constants were calculated and from the intercepts it was possible to evaluate the rate constant for dissociative adsorption of the halogen molecules. At high etchant pressures, where the reaction was half order with respect to Br₂ (or CI₂), a half order "composite" rate constant characterized the etching
reaction. Values for the half order rate constant were determined for a number of wafers at various temperatures. From the temperature dependencies of these rate constants, activation enthalpies of 131±8 and 116±7 kJ mol⁻¹ were calculated for Br₂ and CI₂ etching of intrinsic polycrystalline silicon respectively. A value of 121±7 kJ mol⁻¹ was deterrnined for the Br₂ etching of silicon (100). Higher reaction rates were observed for the etching of n-type polycrystalline silicon, with greater enhancements observed for Br₂ relative to Cl₂ etching. The enhancements in etch rates were found to be principally due to a lower activation enthalpy for the half order rate constant. An activation enthalpy for the composite rate constant of 82±3 kJ mol⁻¹ was determined for Cl₂ etching of n-type silicon with a dopant atom concentration of 5x10¹⁸ atoms cm⁻³. Br₂ etching of the same wafer yielded an activation enthalpy of 86±3 kJ mol⁻¹. At low pressures, the reaction becomes first order and the temperature dependence of the corresponding first order rate constant yielded activation enthalpies of 109 and 83 kJ mol⁻¹ for intrinsic and n-type polycrystalline silicon.Science, Faculty of
Chemistry, Department of
Graduate
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Lohmüller, Elmar [Verfasser]. "Transfer of the Metal Wrap Through Solar Cell Concept to n-Type Silicon / Elmar Lohmüller." Aachen : Shaker, 2016. http://d-nb.info/1081885750/34.
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Morishige, Ashley E. (Ashley Elizabeth). "Metal impurities in n-type crystalline silicon for photovoltaics : simulation, synchrotron-based characterization, and mitigation." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/104131.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 193-211).
Crystalline silicon is the dominant technology in the rapidly-growing photovoltaics (PV) industry, but significant cost reduction is still required before widespread grid parity is achieved. One-quarter of the cost of a PV module is the Si wafer. One way to reduce the cost/kWh of PV is to identify a higher-efficiency "drop-in" substitute for the currently dominant p-type multicrystalline silicon (mc-Si) wafer. This thesis explores one class of wafer substitute: n-type silicon. This material is thought to have higher defect tolerance than p-type, but practical mc-Si cell efficiencies have remained lower than in p-type. This thesis explores why, using a combination of simulation and experiment. In particular, synchrotron-based micro-X-ray fluorescence mapping is used to non-destructively evaluate metal impurity evolution during processing. This thesis demonstrates that metal impurity redistribution during solar cell processing is similar in n- and p-type mc-Si but the relative electrical impact of point defect and precipitated impurities is different, requiring different approaches to processing. It has been hypothesized and shown indirectly that metal impurities redistribute similarly in n- and p-type mc-Si during processing. To confirm this hypothesis, I combined Fermi-level analysis with direct measurements of the metal distribution before and after an industrially-relevant range of gettering processes. This study confirmed that the understanding of metal redistribution developed for p-type mc-Si is directly applicable to n-type mc-Si. To improve the understanding of metal impurity movement during solar cell processing, I developed a tool using Sentaurus TCAD software to visualize in 2D metal redistribution and the resulting recombination activity. I also performed an analytical review of the state of the art of crystalline silicon solar cell process simulation tools. The analysis elucidated the key physics of impurity gettering during solar cell processing and enabled guidelines for efficient, yet accurate, solar cell process simulations. To quantify the recombination activity of precipitated iron in n-type crystalline silicon, I directly measured the iron content and recombination strength of iron precipitates in n-type crystalline silicon using a suite of micro-characterization tools. I found that iron-containing precipitates are highly recombination active in n-type Si and that the precipitate size is correlated with its recombination strength. To enable this study, I benchmarked the use of a new high-throughput synchrotron-based data collection mode called on-the-fly scanning. To bring the level of sophistication of predictive simulation for p-type mc-Si to that of n-type mc-Si, I developed a simulation tool that calculates the redistribution of iron throughout the solar cell process and the resulting injection-dependent electrical performance of the wafer for both p- and n-type Si. Analysis using this tool indicates that p-type mc-Si usually requires point defect remediation during a slow cooling process, but for n-type mc-Si, dissolving iron-rich precipitates during shorter, higher temperature processing is often sufficient. Efficiency entitlement curves predict that n-type mc-Si can support 20% efficient solar cells. Finally, knowledge of defects developed for Si wafers was applied to a key challenge facing the PV industry at the PV system level. In the field, degradation of next-generation industrial p-type mc-Si PV modules has been observed. Leveraging the fundamental understanding of the physics of impurities in Si wafers, the recombination parameters of the root-cause defect were quantified. Building on the rich literature of p-type multicrystalline silicon, this thesis enables predictive engineering of all crystalline silicon materials from wafer growth to module performance in the field.
by Ashley E. Morishige.
Ph. D.
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Oliver, Cyril. "Dopage au Bore du Silicium Multicristallin de type N : application à la fabrication de cellules photovoltaïques par un procédé industriel." Thesis, Montpellier 2, 2011. http://www.theses.fr/2011MON20199/document.
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Cette thèse présente le développement d'un équipement permettant le dopage Bore des cellules photovoltaïques à base de silicium de type n. Un four de diffusion, appartenant à la société Semco Engineering a été développé pour tirer profit du procédé LYDOP (Leaktight Yield Doping en anglais), breveté par la société. Ce dernier a permis la mise au point d'un procédé de diffusion du Bore, régulé sous basse pression, intégrant une source dopante gazeuse à base de BCl3 afin d'effectuer le dopage de plusieurs plaques de silicium simultanément. Les principaux paramètres influençant le procédé de dopage ont été étudiés pour obtenir un dopage très uniforme sur plaque et sur nacelle. Une large gamme de résistances carrées d'émetteurs (de 40 à 100 ohm/sq) a été obtenue avec une uniformité inférieure à 5% sur plaque et sur nacelle. Le développement du procédé de dopage a conduit à étudier deux méthodes de fabrication d'une cellule photovoltaïque sur silicium multicristallin de type n. Plusieurs méthodes pour la formation de l'émetteur Bore sur une seule face ont été présentées : masquage (SiNx, SiO2), dopage back-to-back ou gravure chimique. De cette étude, deux procédés de fabrication (flowcharts) ont été développés pour la fabrication de cellules photovoltaïques : la première par gravure à l'hydroxyde de potassium (KOH) de l'émetteur, la seconde en effectuant le dopage bore des cellules en position back-to-back (dos à dos). Un rendement sur cellule de 13,2% et 14,4% a été obtenu respectivement pour chacune des flowcharts. Ces résultats, limités principalement par les étapes de passivation et de métallisation permettent de démontrer l'utilisation du procédé Bore comme solution à la formation des émetteurs p+This thesis presents the development of an equipment for boron doping of n-type multicrystalline silicon solar cells. A diffusion furnace was developed by Semco Engineering Company. It was built using LYDOP (LeakTight Yields DOPing) technology, patented by Semco. This one permits a simultaneous doping of a big amount of silicon wafers using regulated low pressure processes. Boron diffusion process development was carried out using LYDOP's specifications with BCl3 as gaseous doping source. Main parameters have been studied to control diffusion process. Several sheet resistance values of emitters were achieved (from 40 to 100 ohm/sq) with uniformity under 5% within wafer and within boat by tuning process parameters. Doping process development leads us to investigate how to create a single side emitter with n-type multicrystalline solar cells. Two fabrications flowcharts were presented: one using KOH emitter etches on backside and the other using back-to-back positioning during boron diffusion. Comparison between both flowcharts carried out to 13,2% and 14,4% efficiencies solar cells, respectively on each flowchart. Results are limited by passivation and metallization of emitters. However boron diffusion process demonstrate that LYDOP technology is well adapted to develop n-type solar cells
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Schutz-Kuchly, Thomas. "Investigation du silicium de qualité solaire de type n pour la fabrication de cellules photovoltaïques." Phd thesis, Aix-Marseille Université, 2011. http://tel.archives-ouvertes.fr/tel-00809386.
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Ce travail étudie le potentiel du silicium de type n purifié par voie métallurgique pour la fabrication de cellules photovoltaïques à bas coût. Les teneurs élevées en dopants conduisent à de faibles valeurs de résistivité, ainsi qu'à une diminution de la durée de vie des porteurs de charge. La fabrication de cellules photovoltaïques a permis d'obtenir des rendements de conversion variant de 13.7% à 15.0% sur 148.6cm². Avec un procédé de fabrication amélioré, des rendements de 16.0% pourraient être obtenus. La résistivité des plaquettes a été identifiée comme facteur limitant les performances des cellules. Le co-dopage au gallium a été proposé pour augmenter la gamme de résistivité. Les cellules photovoltaïques réalisées montrent une excellente stabilité sous illumination et de faibles coefficients en température de la tension de circuit-ouvert. Ces travaux de thèse ont permis de définir le potentiel du silicium de type n purifié par voie métallurgique et de définir les spécifications nécessaires initiales au niveau de la charge à purifier pour permettre la fabrication de cellules photovoltaïques efficaces.
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Bock, Robert [Verfasser]. "Screen-printed aluminium-doped p+ emitters for the application to n-type silicon solar cells / Robert Bock." Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover (TIB), 2011. http://d-nb.info/1017379106/34.
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Kakanakova-Georgieva, Anelia, Daniel Nilsson, Xuan Thang Trinh, Urban Forsberg, Son Tien Nguyen, and Erik Janzén. "The complex impact of silicon and oxygen on the n-type conductivity of high-Al-content AlGaN." Linköpings universitet, Halvledarmaterial, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-91731.
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Issues of major relevance to the n-type conductivity of Al0.77Ga0.23N associated with Si and O incorporation, their shallow donor or deep donor level behavior, and carrier compensation are elucidated by allying (i) study of Si and O incorporation kinetics at high process temperature and low growth rate, and (ii) electron paramagnetic resonance measurements. The Al0.77Ga0.23N composition correlates to that Al content for which a drastic reduction of the conductivity of AlxGa1−xN is commonly reported. We note the incorporation of carbon, the role of which for the transport properties of AlxGa1−xN has not been widely discussed.
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Wehmeier, Nadine [Verfasser]. "Fabrication and analysis of co-diffused n-type silicon solar cells applying plasma-deposited diffusion sources / Nadine Wehmeier." Hannover : Technische Informationsbibliothek (TIB), 2017. http://d-nb.info/1136294945/34.
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Madhavi, S. "Carrier Mobility And High Field Transport in Modulation Doped p-Type Ge/Si1-xGex And n-Type Si/Si1-xGex Heterostructures." Thesis, Indian Institute of Science, 2000. http://hdl.handle.net/2005/294.
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Modulation doped heterostructures have revolutionized the operation of field effect devices by increasing the speed of operation. One of the factors that affects the speed of operation of these devices is the mobility of the carriers, which is intrinsic to the material used. Mobility of electrons in silicon based devices has improved drastically over the years, reaching as high as 50.000cm2/Vs at 4.2K and 2600cm2/Vs at room temperature. However, the mobility of holes in p-type silicon devices still remains comparatively lesser than the electron mobility because of large effective masses and complicated valence band structure involved. Germanium is known to have the largest hole mobility of all the known semiconductors and is considered most suitable to fabricate high speed p-type devices. Moreover, it is also possible to integrate germanium and its alloy (Si1_zGex ) into the existing silicon technology.
With the use of sophisticated growth techniques it has been possible to grow epitaxial layers of silicon and germanium on Si1_zGex alloy layers grown on silicon substrates. In tills thesis we investigate in detail the electrical properties of p-type germanium and n-type silicon thin films grown by these techniques. It is important to do a comparative study of transport in these two systems not only to understand the physics involved but also to study their compatibility in complementary field effect devices (cMODFET).
The studies reported in this thesis lay emphasis both on the low and high field transport properties of these systems. We report experimental data for the maximum room temperature mobility of holes achieved m germanium thin films grown on Si1_zGex layers that is comparable to the mobility of electrons in silicon films. We also report experiments performed to study the high field degradation of carrier mobility due to
"carrier heating" in these systems. We also report studies on the effect of lattice heating on mobility of carriers as a function of applied electric field.
To understand the physics behind the observed phenomenon, we model our data based on the existing theories for low and high field transport. We report complete numerical calculations based on these theories to explain the observed qualitative difference in the transport properties of p-type germanium and ii-type silicon systems. The consistency between the experimental data and theoretical modeling reported in this work is very satisfactory.
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Letty, Elénore. "Identification and neutralization of lifetime-limiting defects in Czochralski silicon for high efficiency photovoltaic applications." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI094/document.
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Les cellules photovoltaïques à base de silicium cristallin représentent plus de 90% du marché photovoltaïque mondial. Des architectures de cellules à haut rendement de conversion sont actuellement développées. Pour atteindre leurs performances maximales, ces architectures nécessitent néanmoins une amélioration des propriétés électriques des substrats de silicium cristallin. Les objectifs de cette thèse sont d’identifier les défauts limitant les propriétés électriques de ces substrats, de comprendre les mécanismes menant à leur formation et de proposer des moyens permettant leur neutralisation. Les matériaux étudiés sont des plaquettes de silicium Czochralski de type n, généralement utilisé pour les applications à haut rendement. Le four de tirage Czochralski a d’abord été modélisé afin de comprendre comment le passé thermique subi par le lingot de silicium lors de la cristallisation affecte la génération des défauts. Ces travaux ont été confirmés via des confrontations avec des données expérimentales, en utilisant une méthode originale développée dans le cadre de ce travail. Nous avons ensuite étudié l’influence du budget thermique lié aux procédés de fabrication des cellules sur la population de défauts. Nous avons ainsi pu montrer que la nature des défauts limitant les propriétés électriques du silicium était grandement modifiée selon le procédé de fabrication de cellules utilisé. Nous avons en outre mis en évidence une dégradation inattendue des propriétés électriques du silicium Czochralski de type n sous illumination, liée à la formation d’un défaut volumique inconnu. Les conditions de formation et de suppression de ce défaut ont été étudiées en profondeur. Enfin, les principaux défauts limitant les propriétés électriques du silicium ayant été identifiés et les mécanismes menant à leur formation compris, nous proposons dans un dernier chapitre des nouvelles techniques de caractérisation permettant de détecter les plaquettes défectueuses en début de ligne de production de cellules photovoltaïques, et ce à une cadence industriellePhotovoltaic solar cells based on crystalline silicon represent more than 90% of the worldwide photovoltaic market. High efficiency solar cell architectures are currently being developed. In order to allow their maximal performances to be reached, the electronic properties of their crystalline silicon substrate must however be enhanced. The goals of the present work are to identify the defects limiting the electronic properties of the substrate, to understand the mechanisms leading to their formation and to propose routes for their neutralization. The studied materials are n-type Czochralski silicon wafers, usually used as substrates for high efficiency photovoltaic applications. The Czochralski puller was first modeled in order to understand how the thermal history experienced by the silicon ingot during crystallization affects the defects generation. This study were validated through the comparison with experimental data using an original method developed in the frame of this work. We then studied the influence of the thermal budget associated to solar cell fabrication processes on the defects population. We thus showed that the nature of lifetime-limiting defects was completely changed depending on the solar cell fabrication process. Besides, we evidenced an unexpected degradation of the electronic properties of n-type Czochralski silicon under illumination, related to the formation of an unknown bulk defect. The formation and deactivation features of this defect were extensively studied. Finally, the main limiting defects being identified and the mechanisms resulting in their formation understood, we propose in a last chapter new characterization techniques for the detection of defective wafers at the beginning of production lines at an industrial throughput
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Stockmeier, Ludwig [Verfasser], and Lothar [Gutachter] Frey. "Heavily n-type doped silicon and the dislocation formation during its growth by the Czochralski method / Ludwig Stockmeier ; Gutachter: Lothar Frey." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2018. http://d-nb.info/1153608928/34.
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Machado, Taila Cristiane Policarpi Alves. "Implementa??o de emissores p+com diferentes dopantes para c?lulas solares n+np+ finas." Pontif?cia Universidade Cat?lica do Rio Grande do Sul, 2018. http://tede2.pucrs.br/tede2/handle/tede/8010.
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Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES
The solar cells manufactured in n-type silicon, doped with phosphorus, do not present light induced degradation and they have the potential of achieving high efficiency due to the larger minority charge carrier lifetime. Besides, they are less susceptible to contamination by metal impurities. The aim of this work was to analyze different dopants to obtain the p+ region in n+np+ solar cells manufactured in Czochralski silicon wafers, solar grade, n-type, 120 ?m thick. The acceptor impurities used were B, Al, Ga, GaB and AlGa, deposited by spin-on and diffused at high temperature. The temperature, time and gases used in the process of diffusion were ranged. The sheet resistances (R?) of the diffused regions and the impurity concentration profiles were measured. We concluded that the B and GaB can be diffused at 970? C for 20 min to obtain p+ emitters with values of R? suitable to the production of solar cells with screenprinted metal grid. The Ga and AlGa require high temperatures (greater than 1100? C) and long times to produce doping profiles compatible with the production of solar cells. The Al did not produce low sheet resistance regions, even at temperatures of 1100? C. The use of argon gas instead of the nitrogen did not lead to the decreasing of the sheet resistance. The GaB is the only one doping material analyzed that can be a viable replacement for the B in the production of p+ emitter in n-type solar cells.The GaB was the only one doping material analyzed that allowed the manufacture of solar cells with the maximum efficiency of 13.5%, with the diffusion performed at 1020? C for 20 min. The FF was the main parameter that reduced the efficiency of solar cells doped with GaB when compared to the boron doped cells due to a lower shunt resistance. The n+np+ solar cell, 120 ?m thick, that achieved the highest efficiency was doped with boron and reached 14.9%, a value higher than the previously obtained in studies in the NT-Solar with thin silicon wafers.
As c?lulas solares fabricadas em l?minas de sil?cio tipo n, dopadas com f?sforo, n?o apresentam degrada??o por ilumina??o e t?m potencial de obten??o de maior efici?ncia devido ao maior valor do tempo de vida dos portadores de carga minorit?rios. Adicionalmente, s?o menos suscept?veis ? contamina??o por impurezas met?licas. O objetivo deste trabalho foi realizar uma an?lise de diferentes dopantes para obten??o da regi?o p+ em c?lulas solares n+np+fabricadas em l?minas de sil?cio Czochralski, grau solar, tipo n, com espessura de 120 ?m. Os elementos aceitadores utilizados foram o B, Al, Ga, GaB e AlGa, depositados por spin-on e difundidos em alta temperatura. Foram variadas as temperaturas, os tempos e os gases utilizados no processo de difus?o. Foi medida a resist?ncia de folha (R?) das regi?es difundidas e o perfil de concentra??o de impurezas em fun??o da profundidade. Foram desenvolvidas c?lulas solares com B, Ga, GaB e Al. Verificou-se que o B e GaB podem ser difundidos em temperatura de 970 ?C e por 20 min para obten??o de emissores com valores de R? compat?veis com a produ??o de c?lulas solares metalizadas por serigrafia. O Ga e AlGa necessitam de altas temperaturas (maiores que 1100 ?C) e tempos elevados para produzir perfis de dopantes compat?veis. O Al n?o produziu regi?es p+ de baixa R?, mesmo com a difus?o a 1100 ?C. O uso de Ar para substituir o N2 n?o acarretou em diminui??o da resist?ncia de folha. O GaB foi o ?nico dopante analisado que permitiu a fabrica??o de c?lulas solares com efici?ncia m?xima de 13,5 %, com difus?o a 1020 ?C por 20 min. O fator de forma foi o principal par?metro que reduziu a efici?ncia dos dispositivos com GaB quando comparado ao valor obtido com B devido a menor resist?ncia em paralelo. A c?lula solar n+np+ de 120 ?m de maior efici?ncia produzida neste trabalho foi dopada com boro e atingiu a efici?ncia de 14,9 %, sendo maior que as anteriormente obtidas em trabalhos realizados no NT-Solar com l?minas finas.
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Mojrová, Barbora. "Solární články z monokrystalického křemíku typu n s vysokou účinností." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2019. http://www.nusl.cz/ntk/nusl-408053.
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Tato dizertační práce je zaměřena vývoj a ověřování nových postupů přispívajících ke zvýšení účinnosti bifaciálních solárních článků založených na monokrystalickém křemíku n-typové vodivosti. Tato práce přináší nové poznatky o vylepšených výrobních procesech a postupech použitých během výroby článků v ISC Konstanz. V rámci práce byly vyrobeny solární články typu n-PERT (Passivated Emitter Rear Totally diffused) s vysokou účinností, a to pomocí standartních procesů a zařízení používaných běžně při průmyslové výrobě. Zapojení těchto průmyslových postupů a metod umožnilo ověřit možnosti výroby n-typových článků za použití téměř totožného vybavení, jaké je potřeba pro výrobu p-typových článků. Zvýšení účinnosti bylo založeno především na vylepšení jednotlivých procesních kroků. Experimenty popsané v této práci dosvědčují zlepšení procesu difúze bóru, přizpůsobení parametrů pasivační a antireflexní vrstvy nově navrženému emitoru, zlepšení procesu metalizace ve smyslu využití past neobsahujících hliník, testování tisku rozličných motivů spolu s různými sekvencemi výpalu. V rámci práce byla testována možnost zamezení jevu potenciální indukované degradace (Potential Induced Degradation – PID) pomocí vhodného složení ARC a pasivační vrstvy. Vyrobené n-typové solární články dosáhly maximální hodnoty účinnosti 20,9 %.
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Śledziewski, Tomasz [Verfasser], Heiko B. [Akademischer Betreuer] Weber, and Martin [Gutachter] Hundhausen. "Electrical characterization of n-type 4H silicon carbide with improved material and interface properties using advanced doping techniques / Tomasz Śledziewski ; Gutachter: Martin Hundhausen ; Betreuer: Heiko B. Weber." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2018. http://d-nb.info/1170959156/34.
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Maslougkas, Sotirios. "Gate oxide characterization of 4H-SiC MOS capacitors : A study of the effects of electrical stress on the flat-band voltage of n-type substrate 4H-SiC MOS capacitors." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-301848.
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Silicon is the main material used in electronics. The evolution of power electronics and the need for more power efficient semiconductor devices led silicon to its limits. Silicon carbide is a promising material for electronic applications with a wide band-gap, high critical electric field, high thermal conductivity and saturation velocity. Except from its superiority to silicon, silicon carbide comes with a drawback of about two orders of magnitude more interface traps in the SiC/SiO2 interface compared with silicon. A result of this drawback is a flat-band voltage shift when applying a stress to the gate of MOS capacitors and power MOSFETs. In order to study the pure characteristics of the SiC/SiO2 interface, two stress methods, a current pulse stress and gate voltage upsweep, have been applied on 4H-SiC capacitors with nitrided thermal oxides at room temperature and at higher temperatures. The flat-band voltage recovery was examined. The flat-band voltage could be restored at room temperature with a gate voltage downsweep while a restoration is not needed at higher temperatures. The maximum voltage (initial voltage) and the voltage rate of the downsweep were investigated and higher initial voltages and lower voltage rates showed to lead to better VFB restoration. A 200 millisecond long current pulse stress was implemented and it had almost similar effects as the voltage upsweep which lasts 50 seconds.Kisel är det viktigaste materialet som används i elektronik. Utvecklingen av kraftelektronik och behovet av mer energieffektiva halvledarkomponenter ledde kisel till sina gränser. Kiselkarbid är ett lovande material för elektroniska applikationer med ett brett bandgap, högt kritiskt elektriskt fält, hög värmeledningsförmåga och hög mättningshastighet. Förutom dess överlägsenhet gentemot kisel, kommer kiselkarbid med en nackdel med cirka två storleksordningar fler gränssnittsfällor i SiC / SiO2-gränssnittet jämfört med kisel. Ett resultat av denna nackdel är en förskjutning av flatbands-spänningen, VFB, när man applicerar en spänning på gaten till MOS-kondensatorer och kraft- MOSFETar. För att studera de rena egenskaperna hos SiC/SiO2-gränssnittet har två spänningsmetoder, en strömpulsstress och ett uppåtriktat gate-spänningssvep, applicerats på 4H-SiC- kondensatorer med nitriderade termiska oxider vid rumstemperatur och vid högre temperaturer. Återställning av VFB undersöktes. VFB kan återställas vid rumstemperatur med ett nedåtriktat gate-spänningssvep medan en återställning inte behövs vid högre temperaturer. Den maximala spänningen (initialspänningem) och svephastigheten för det nedåtriktade svepet undersöktes och högre initialspänningar och lägre svephastigheter visade sig leda till bättre VFB-återställning. En 200 millisekund lång strömpuls-stress implementerades och den hade nästan samma effekter som ett uppåtriktat spänningssvep
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Printz, Martin [Verfasser], and T. [Akademischer Betreuer] Müller. "Entwicklung von strahlenharten N-in-P Silizium-Teilchendetektoren und Studien von Triggermodulen für den CMS Detektor am LHC = Development of radiation-hard n-in-p type silicon detectors and studies on modules with transverse momentum discrimination for the CMS detector at the LHC / Martin Printz. Betreuer: T. Müller." Karlsruhe : KIT-Bibliothek, 2016. http://d-nb.info/1088553583/34.
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Gabouze, Noureddine. "Etude photoelectrochimique de gaas(n) et si(n) en milieu non aqueux ch::(3)oh et ch::(3)cn : etude et realisation de cellules photoelectrochimiques minces." Paris 6, 1988. http://www.theses.fr/1988PA066242.
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L'etude electrochimique et photoelectrochimique des jonctions semiconducteur-electrolyte non aqueux (ch::(3)oh et ch::(3)cn) de gaas et si permet de mettre en evidence les proprietes de surface de ces materiaux. Realisations des cellules minces (pec), gaas(ch::(3)oh)sno::(2) montrent des rendements de conversion de l'ordre de 12 a 13%
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Grasa, Molina María Isabel. "EPR-induced charge transport in highly doped crystalline n-type silicone carbide." [S.l. : s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=961541768.
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Maldonado, Daniel. "Volumétrie d'adsorption de N-Hexane sur silices de type MCM-41 : Une étude thermodynamique de la condensation dans les mésopores." Montpellier 2, 2004. http://www.theses.fr/2004MON20150.
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Fekkar-Nemmiche, Nadia. "Caractérisations physicochimiques de silices mésoporeuses fonctionnalisées du type SBA-15 : étude thermodynamique et dynamique du confinement de l’eau, du 1-pentanol et du n-heptane dans ces silices." Montpellier 2, 2009. http://www.theses.fr/2009MON20077.
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Ce travail est consacré à l'étude des propriétés physico-chimiques de silices mésoporeuses fonctionnalisées du type SBA-15. Il a consisté à caractériser i) la structure mésoporeuse par DRX et par isothermes d'adsorption d'azote, ii) les états de surface de la silice par RMN lorsqu'on passe d'une fonction propyle à une chaîne -CH2-CH2-CH2-PO(OX)2 où X=Et, H, Li, Na et K, iii) les propriétés de confinement de trois adsorbats (eau, 1-pentanol et n-heptane) par analyses thermiques et iv) les propriétés de conduction ionique par spectroscopie d'impédance complexe. L'examen de la microstructure par RMN du solide a permis de mettre en évidence que la substitution des silanols de surface des pores des silices étudiées par des groupements tétraméthylsilyles (-Si(CH3)3) n'était pas totale. Les analyses par DSC des silices exposées la vapeur saturante d'eau, de 1-pentanol ou de n-heptane ont révélé que les températures de transitions de phase du fluide confiné dans les pores sont modifiées par rapport à celles du fluide en volume étendu. Ceci est dû à l'effet combiné d'une dimension réduite et de l'interface fluide–mur, siège d'interactions spécifiques liées à la nature (polaire ou apolaire) des groupements introduits à la surface des pores. En présence d'eau confinée, les analyses RMN ont montré que celle-ci conserve sa coordination tétraédrique et que la mobilité des chaînes à la surface des pores augmente. L'étude de la conductivité par SIC des silices soumises à la vapeur saturante d'eau, de 1-pentanol ou de n-heptane indique que tous les solides étudiés sont des isolants tant qu'il n'y a pas de phase adsorbée. Lorsqu'une conductivité apparait, elle est de type ioniqueThis work is devoted to the study of physico-chemical properties of mesoporous functionalized silica SBA-15. It has particularly been axed to the characterization of i) the mesoporous structure by XRD and N2 adsorption- desorption isotherms, ii) the analysis by solid NMR of the surface states, iii) the properties of confinement of three adsorbates (water, 1-pentanol, n-heptane) by thermal analysis and iv) the properties of ionic conduction by complex impedance spectroscopy. The microstructure examination by solid NMR has revealed that the substitution of the silanols of nanopores surface by tetramethylsilyle -Si(CH3)3 groups was not complete. This work explored the surface functionalization when moving gradually from a -CH2-CH2-CH3 groups to -CH2-CH2-CH2-PO(OX)2 or X = Et, H, Li, Na and K groups. The DSC analysis of silica exposed vapour pressure of water, 1-pentanol or n-heptane showed that temperatures of phase transitions of the fluids are modified by confinement compared to those of the bulk state. These changes are related to a combination of small size and the fluid-wall interactions which depend on the nature (polar or apolar) of functional groups introduced on the surface pores. In the presence of confined water the NMR analysis indicates that the mobility of the functional chains on the surface of pores increases. The confined water retains its tetrahedral coordination. The study of conductivity by CIS of the silica samples previously dried and then exposed to vapour pressure of water, 1-pentanol and n-heptane indicates that all samples studied are insulators if there is no adsorbed phase. When a conductivity appears suggests that it is of ionic type
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Tsai, Meng-Han, and 蔡孟翰. "Surface Passivation on N-type Silicon Solar Cells." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/41704707508113103834.
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碩士國立臺灣大學
電子工程學研究所
100
Wafer based solar cell accounts for the production of a large part in photovoltaic industry due to its stability and high efficiency. Although the technology of wafer based solar cell has been well-developed for conventional structure, there are still numerous new challenges existing for the high efficiency solar cell. In this thesis, the fabrication process of n-type crystalline silicon solar cell is demonstrated by using ion implantation to form the boron (p+) emitter and phosphorous (n+) back surface field. By means of appropriate annealing, the implanted dopants could be activated, and the damage caused by the implantation can be repaired. Moreover, surface passivation plays an important role in promoting the efficiency of cells due to its strong dependence of open circuit voltage (Voc). Therefore, the mechanism and characteristic of surface passivation were introduced in this work. Then, different passivation layers were designed and analyzed by quasi-steady-state photoconductance and photoluminescence (QSSPC) measurement. In this work, the SiNx/Al2O3 stack layers could provide the best passivation quality. And with the excellent passivation of SiNx/Al2O3 stack layers, efficiency more than 18% is shown in this work.
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Wen, Chung-Chi, and 溫宗錡. "Plasmon-Enhanced Auger Recombination in n-Type Silicon." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/04299615013818629263.
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碩士國立交通大學
電子研究所
105
The effects of many-body plasmons on the Auger recombination in doped semiconductors were less studied over the past five decades. Recent first-principles calculations on n-type silicon, without participation of plasmons, yielded Auger lifetimes that are higher than experimental values. In this thesis, we make use of an existing microscopic Auger recombination formalism with which to reproduce first-principles results. Plasmons-enhanced potential fluctuations are not faster than the Auger event; therefore, the effect of plasmons can have only the indirect effect in the long wavelength limit: the experimental electrical bandgap narrowing and the experimental electron temperature. The electrical bandgap narrowing is found to be weak in determining the Auger lifetime. On the contrary, the plasmons-induced conduction electron heating is determined to be the dominant mechanism. The calculated results with electron heating included are consistent with the experimental observations.
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Huang, Yu-Hung, and 黃昱閎. "N-type silicon based homojunction and heterojunction solar cells." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/83478367825654828285.
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碩士國立臺灣大學
電子工程學研究所
99
Wafer based solar cell accounts for the production of a large part in photovoltaic industry due to its stability and high efficiency. Although the technology of wafer based solar cell has been well-developed for conventional structure, there are still numerous new challenges existing for high efficiency solar cell. In this thesis, the fabrication process of n-type silicon based homojunction solar cell is demonstrated by using ion implantation to form the boron (p+) emitter and phosphorous (n+) back surface field. By using appropriate annealing condition, The implanted dopants and damage introduced by implantation can be activated and repaired, respectively. Both rapid thermal annealing (RTA) and furnace annealing were investigated within this work. The efficiency is 14.5% by RTA process and 15.8% by furnace annealing process. Moreover, contact formation, contact material, and contact thickness conditions are taken into consideration for better efficiency. Therefore, experiments of various annealing conditions in forming gas after depositing contact, different material, and the thickness of contact are designed in this work. Next, surface passivation is very important for solar cell efficiency due to its strong dependence on open circuit voltage so it affects solar cell efficiency. Aluminum oxide (Al2O3) layers deposited by different method are compared for passivation ability by using quasi-steady-state photoconductance and photoluminescence (QSSPC) measurement. It means better passivation ability to passivate solar cell for higher effective carrier lifetime. In addition, QSSPC measurement also provide a way to estimating the implied open circuit voltage after forming the junction of solar cells. With the excellent passivation of Al2O3 deposited by atomic layer deposition (ALD), the efficiency more than 16% is shown in this work. Finally, the n-type silicon HIT solar cell with 11.1% efficiency is demonstrated to discuss the benefits from amorphous silicon emitter and suitable PDA condition.
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SYU, JIA-IMN, and 許嘉珉. "Fabrication and characteristics of carbon nanotubes/n-type silicon heterojunction." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/56611710321222750864.
Full textAbstract:
碩士南臺科技大學
光電工程系
105
Since the discovery of carbon nanotubes(CNTs), CNTs have attracted intensive interest on nanotechnology due their unique properties, such as high Young modulus, high conductivity, and high field emission efficiency at low turn-on voltage. Many potential applications use their unique properties, ex. silicon hetero-junction solar cells. Methods for the synthesis of CNTs include arc-discharge, laser vaporization, thermal chemical vapor deposition (CVD), plasma enhance chemical vapor deposition (PECVD) and electron cyclotron resonance CVD (ECR-CVD). In consideration of the advantage of high dissociation percentage of the precursor gases and high uniformity of plasma energy distribution, the ECR-CVD is adopted for this study. In this study, multi-walled carbon nanotubes (MWNTs) were synthesized on a silicon substrate at relatively low temperature 500℃, using an ECR-CVD. Mixing gases of Methane (CH4) and Nitrogen (N2) were used as the carbon source and the plasma treated Ni film as the catalyst. Process parameters such as process time, microwave power, and gas flow were altered to optimize the properties of MWNTs on Si. The surface morphologies and microstructures of carbon nanotubes are examined by scanning electron microscopy (SEM). The results show that ECR-CVD grown CNTs reveal vertically aligned character and the length of CNTs is varied from 0.3μm to 2.6μm.The density and uniformity of CNTs can be optimized using the plasma treated Ni catalyst under power of 440W. The signs of the Hall coefficients are negative, indicating that majority carriers are electrons in these films. CNTs/n-Si junction property depends on the density and length of CNTs. The ideality factor (n) of the best CNTs/n-Si junction is equal to one.
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Lee, Chien-Ming, and 李健民. "The Study of Commercial N-type Crystalline Silicon Solar Cell." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/80877835031574667552.
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碩士國立成功大學
光電科學與工程研究所
94
Abstract In this thesis, we use commercial in-line PECVD to deposit SiNx:H antireflection coating layer in low temperature (<300℃) and finish the commercial n-type solar cells by screen printing to achieve high efficiency、low cost and high throughput. The main discussion is the results of different process. Analyzing SiNx layer after different etching time. We use AFM to measure the roughness of surface, FTIR spectrum to analyze the bonding of elements and spectrometer to analyze optical characteristics. Finally we use solar simulator to obtain efficiency and analyze results of different process.
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Dongying, Yang, and 楊東穎. "Effect of annealing on sintering surface of N-type porous silicon." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/87790720516639945768.
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碩士國立中央大學
機械工程學系
103
The aim of this research is to make porous silicon layer on a n-type silicon wafer with the exposure of UV light,which could be used as a kind of solar cell material. Silicon based materiad that can be used in solar cell can be seprate as single crystalline ,polysilicon ,and amorphous silicon , in which single crystal silicon solar cell has best efficiency .In this experiment, we try to make a single crystal layer on the surface of the silicon wafer with the method of thermal annealing . Because of the long time that traditional method cost, we use two different ways to recrystallize the wafer surface and then study the quality difference after two kinds of treatment. The experiment parameters includes time, concentration, illumination, and the temperature, time and environment during anealling. We made difference porous silicon wafers by controlling experiment parameters , and test the quality under different conditions. All these work can be a data base for future work.
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Lee, Po-Wen, and 李博文. "An enhancement method of n-type porous silicon fabrication by Hall effect." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/5gge5e.
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碩士中國文化大學
材料科學與奈米科技研究所
94
In this thesis, the researches focus on the study of the difficult etched porous silicon. Porous has been extensive researched, but the majority study is based on the P-type silicon only, the main reason is that the N-type silicon has less electric holes than the P-type silicon. Therefore, the N-type silicon is more difficult to be etched. The thesis emphasized the used of Hall-effect theory to strengthen the etching of N-type silicon. In order to carry out Hall-effect, the first thing is to design a new tank that can etch trough to oxidizing. This is to make N-type silicon etched at upper and lower electric fields that can exert direction electric current I of X in step, and magnetic field B of Z direction, then let the electron of N-type silicon assemble to the base plate. Then to make the surface layer change into the P-type and carry on the etching of the porous silicon instead. Finally, by changing the size of magnetic field, the irregular pores and pillars occur on the surface of the N-type silicon. Therefore, the pores and the pillars can be controlled.
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Lai, Shih-wei, and 賴世偉. "Fabrication of Solar Cells using Cuprous Oxide on N-type Bulk Silicon." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/34486656442928217725.
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碩士國立中山大學
光電工程學系研究所
104
In this study, we fabricate heteorjunction solar cells which are composed of P-type cuprous oxide on N-type silicon wafer. First, the silicon wafer was textured with KOH alkaline solution to lower the weighted reflection. In the following, we used thermal oxidation to grow silicon oxide on the surface of silicon wafer, and removed the grown oxide with wet etching. There are two reasons to do so. One is to lower the sharpness of pyramid structure, and another is to remove particles which could attach to the silicon surface during fabricating process. Moreover, we do the surface passivation of silicon using supercritical fluid to repair defects. Finally, we deposited P-type cuprous oxide on silicon substrate with both solution process and reactive sputtering and completed the devices by fabricating the metal electrodes. The reflectivity of silicon substrate was reduced from 29.6% to 15.3% by texturizing the Si surface. The SEM pictures also showed that the sharpness of pyramid structure was successfully reduced with thermal oxidation and etching. However, this led to an increase of reflectivity. The reflectivity increased from 15.3% to 17.7% after removing 0.5μm thermal oxide on the Si surface. Finally, the performance of devices was measured by solar simulator at AM1.5. The best devices showed an open circuit voltage (VOC ) of 0.3V、a short circuit current density (JSC) of 1.03mA/cm2、a full factor (FF) of 0.37 and an energy conversion efficiency (η) of 0.11%. The carrier lifetime of the textured silicon wafer which is passivated with supercritical fluid is only 94.1μs. The carrier lifetime must be improved before a high performance Cu2O/n-Si heterojunction solar call can be obtained.
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Deng, Shu-Shuan, and 鄧旭軒. "Fabrication of P type and N type Hydrogenated Microcrystalline Silicon Thin Films Using RF Magnetron Sputtering." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/59858257486560502295.
Full textAbstract:
碩士國立中央大學
光電科學研究所
96
In the last decades, the researches of thin film solar cells have attracted much attention for the reason of the energy crisis. Plasma-enhance chemical vapor deposition (PECVD) is the most popular method to fabricate silicon thin film solar cells. The disadvantages of PECVD are the high facility cost and using the toxic processing gases such as silane (SiH4), B2H6 and PH5. To solve the problem the reactive radio frequency sputtering deposition was applied in this research, which is a safe and cheap method to fabricate the doped hydrogenated microcrystalline silicon without using any toxic gas. The p type and n type hydrogenated microcrystalline silicon (μc-Si:H) thin films were fabricated with the different concentration of the doped target and the hydrogen gas flow. The properties of the films were measured using Alpha–Step, XRD, conductivity, carrier concentration, carrier mobility, and activation energy measurement. The results show that when the boron grains occupied 30% of the p type silicon target area and hydrogen flow 9sccm, the best conductivity is achieved at about 3.79×10-2 S/cm for the p type μc-Si:H thin film. The μc-Si:H grain size is 4.84nm in the film. The activation energy is 0.044ev. Using Hall measurement, the carrier concentration is achieved at 3.34×1018cm-3 and carrier mobility 0.516cm2/V-S. Besides, when n type silicon wafer occupied 75% of the silicon target area and hydrogen flow 7sccm for the n type μc-Si:H thin film, the best conductivity is achieved at about 9.66×10-3 S/cm. The μc-Si:H grain size is 12.5nm in the film. The activation energy is 0.11ev. Using Hall measurement, the carrier concentration is achieved at 1.11×1018cm-3 and carrier mobility 0.525cm2/V-S. Both results have met the requirements of p type and n type μc-Si:H thin films for the application of thin film solar cells.
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Li, Liang-Zheng, and 李良政. "Simulation design of a high-speed P-N junction-type silicon electrooptical modulator." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/44572926940241238339.
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碩士華梵大學
電子工程學系碩士班
97
The study of this thesis is to simulate the device characteristics of a high-speed P-N junction-type silicon electrooptical modulator and a Mach-Zehnder interferometer using the rib/ridge waveguide structure and free carrier plasma dispersion. During the simulation, we used the silicon-on-insulator (SOI) wafer of general specifications. We also used the BeamPROP optical software, T-suprem4 semiconductor process software, and MEDICI semiconductor electrical characteristics software to design a high-speed P-N junction-type silicon electrooptical modulator at the wavelength of 1550 nm. Under the process conditions of the National Nano Device Laboratory, we simulated and adjusted a variety of parameters such as P-N junction concentration (1015, 1016, 1017 cm-3), ion implantation energy (50, 100, 150, 200 keV) and diffusion temperature (1000, 1050, 1100 oC) and so forth to observe their impact on an electrooptical modulator. We then determined the optimum process parameters of our devices. We got from the thesis the following information: implantation energy had little effect on the diffusion time, operation speed, maximum change of the refractive index (Δn), and maximum change of light absorption (Δα) of a electrooptical modulator; junction concentration had obvious effect on the device length, operation speed, maximum change of the refractive index and maximum change of light absorption, and then diffusion temperature just affected the diffusion time. That the implantation energy is 200 keV, the diffusion temperature is 1100 oC, and the P-N junction concentration is 1017 cm-3 is the optimum process condition of our electrooptical modulator. At the reverse bias of a step-like voltage of 3 V, the highest operation speed of the modulator device is 25GHz, the maximum change of refractive index is 2.4×10-4, and the maximum change of light absorption is about 0.7 cm-1. In addition, the length of a Mach-Zehnder interference designed is 4.7cm. This length can further be shortened to 1 ~ 2 cm by reducing the thickness of the epitaxial layer of a SOI wafer.
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Huang, Hao-Chien, and 黃皓堅. "Grain Control and Gettering of N-type Multi-Crystalline Silicon for Photovoltaic Applications." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/06680562352760063369.
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碩士國立臺灣大學
化學工程學研究所
99
N-type silicon solar cell has attracted notice recently because of its high endurance to common impurity and higher minority carrier lifetime than p-type silicon. We have grown n-type mc-silicon crystal and control the resistivity distribution from 0.5 to 1.5 (Ω-cm). The active cooling spot was implemented at crucible bottom to control the grains and side insulation to enhance the grain size in n-type mc-silicon during directional solidification. The EBSD mapping of controlled ingot was measured to investigate the effect on active cooling spot, we also find out the grain orientation in the top of ingot was {112} dominant, and the minority carrier lifetime increased with the height of ingot. The wafers were also etched with a Seco solution to detect crystallographic defects by metallographic microscope and Photoluminescence images. The etch-pits density at the top wafer of controlled ingot had the lowest value about 103 cm-2. Finally, we used the phosphorus gettering to remove impurity from the wafers of controlled ingot, and its enhanced the lifetime of the controlled wafer.
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LUN, CAI BING, and 蔡秉倫. "Study of N-type Crystalline Silicon Solar Cell Fabricated with Rear Al Emitter." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/fuagsg.
Full textAbstract:
碩士中華大學
電機工程學系碩士班
101
Abstract In this thesis, we have successfully fabricated the n-type crystalline silicon solar cell devices with rear Al emitter. The bare wafer is grown by Czochralski crystal growth method, direct (100), resistivity about 1.5~5.5Ω-cm. Here, we choose n-type wafer because n-type wafer has many advantages, such as better tolerances of metal impurities, fewer boron-oxygen bonds (solar cell performance decreases slightly), higher minority carrier lifetime, better fabrication processes which can be integrated directly to commercial solar cell fabrication processes. Compared with another n-type crystalline silicon solar cell structure with boron emitter, the boron emitter doped by furnace has non-uniform and residual material problems. Therefore, we adopt n-type crystalline silicon solar cell with rear Al emitter in the study for production mode. The study topic can be divided into two parts, the first one is the optimization of phosphorous doping profile; the other one is developed of the front surface heavy doping structure in local region. The rear aluminium emitter of device is fabricated by Al paste in the rear surface. After firing, the Al and silicon would be combined into the formation of aluminium-silicon alloy. The Al would diffuse in the rear n-type region and transform into p+ region, and formed homogeneous rear pn junction. Finally, the front surface is passivated by the SiNx layer. For the first part, the experiment is focused on the optimization of front side phosphorous doping profile because the pn junction in rear surface is not easy to adjust. According to better front side field, it can increase the device performance. The higher phosphorous concentration would increase higher surface recombination velocity and decrease contact resistivity. Therefore, the optimization phosphorous doping profile can be benefited to the front surface recombination velocity, lower contact resistivity, and higher short circuit current. Compared with pilot run devices, the device efficiencies with optimized phosphorous doping profile can be increased from 17.55 to 17.96%. The second part is using self-align technology in the front side field of device to increase the device performance. The fabrication processes of the front side heavy doping region in local area are shown in below. We use the SiNx layer as a mask to protect the contact region. The wet oxidation step is fabricated by furnace, removed SiO2 layer by HF ,and to form the lightly doping region. At the same time, we also adjust the doping concentration, depth, and the wet oxidation time to achieve better device performance, such as lower surface recombination velocity, and better ohmic contact. Compared with the efficiency of device with better POCl3 doping profile, the devices using self-align technology can be enhanced from 17.96 to 19.2%. Key word: rear Al emitter, n-type crystalline silicon, solar cell
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Lin, Kuan-Bo, and 林冠伯. "Co-diffusion by spin-on dopants for bifacial n-type silicon solar cells." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/24qx9d.
Full textAbstract:
碩士國立中央大學
材料科學與工程研究所
103
In conventional bifacial n-Si solar cells fabrication processing, raw Si wafers have to be annealed in high temperature furnace at least two times to form emitter and back surface field (BSF). However, these processing have many disadvantages and waste time in the industrial. In this thesis, we used the co-diffusion by spin-on dopants processing to form the p+ emitter and n+ BSF in the ONE step for n-type Si which could reduce the annealing time and manufacturing cost in the industrial. The two structures were fabricated to diffuse in high temperature and characterized in SIMS profiles, effective lifetime, inverse saturation current density and surface recombination velocity (SRV). Finally, the structure in highly performance for surface passivation were fabricated in bifacial n-Si solar cells in order to improve and modify the conventional manufacturing method. As our result showed, co-diffusion structure for barrier layer on phosphorous side had better surface passivation properties. This structure would be demonstrated in the bifacial n-Si solar cells for efficiency = 11.4 %, Voc = 591.6 mV, Jsc = 33.6 mA/cm2 and fill factor = 62 %.