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1
Bracht, Hartmut, S. Brotzmann, and Alexander Chroneos. "Impact of Carbon on the Diffusion of Donor Atoms in Germanium." Defect and Diffusion Forum 289-292 (April 2009): 689–96. http://dx.doi.org/10.4028/www.scientific.net/ddf.289-292.689.
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We report experiments on the diffusion of n-type dopants in isotopically controlled Ge multilayer structures doped with carbon. The diffusion profiles reveal a strong aggregation of the dopants within the carbon-doped layers and a retarded penetration depth compared to dopant diffusion in high purity natural Ge. Dopant aggregation and diffusion retardation is strongest for Sb and similar for P and As. Successful modeling of the simultaneous self- and dopant diffusion is performed on the basis of the vacancy mechanism and additional reactions that take into account the formation of carbon-vacancy-dopant and dopant-vacancy complexes. The stability of these complexes is confirmed by density functional theory calculations. The overall consistency between experimental and theoretical results supports the stabilization of donor-vacancy complexes in Ge by the presence of carbon and the dopant deactivation via the formation of dopant-vacancy complexes. These results help to develop concepts to suppress the enhanced diffusion of n-type dopants and the donor deactivation in Ge. Both issues hamper the formation of ultra shallow donor profiles with high active dopant concentrations that are required for the fabrication of Ge-based n-type metal oxide semiconductor field effect transistors.
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Khina, Boris B. "Extended 'Five-Stream' Model for Diffusion of Implanted Dopants in Silicon during Ultra-Shallow Junction Formation in VLSI Circuits." Defect and Diffusion Forum 277 (April 2008): 107–12. http://dx.doi.org/10.4028/www.scientific.net/ddf.277.107.
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Ion implantation of different dopants (donors and acceptors) into crystalline silicon with subsequent thermal annealing is used for the formation of ultra-shallow p-n junctions in VLSI technology. The experimentally observed phenomenon of transient enhanced diffusion (TED) during annealing hinders further downscaling of advanced VLSI circuits. However, modern mathematical models of dopant diffusion, which are based on the so-called “five-stream” approach, and software packages such as SUPREM4 encounter difficulties in describing TED. In this work, an extended five-stream model for diffusion in silicon is developed, which takes into account all the possible charge states of point defects (vacancies and silicon self-interstitials) and diffusing pairs “dopant atom–vacancy” and “dopant atom–silicon self-interstitial”. The model includes diffusion and drift of differently charged point defects and pairs in the internal electric field and the kinetics of interaction between unlike species. The expressions for diffusion fluxes and sink/source terms that appear in the non-linear, non-steady-state reaction-diffusion equations are derived for both donor and acceptor dopants accounting for multiple charge states of the diffusing species.
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Drabczyk, Kazimierz, Edyta Wróbel, Grazyna Kulesza-Matlak, Wojciech Filipowski, Krzysztof Waczynski, and Marek Lipinski. "Comparison of diffused layer prepared using liquid dopant solutions and pastes for solar cell with screen printed electrodes." Microelectronics International 33, no. 3 (2016): 167–71. http://dx.doi.org/10.1108/mi-03-2016-0031.
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Purpose The purpose of this study is comparison of the diffusion processes performed using the commercial available dopant paste made by Filmtronics and the original prepared liquid dopant solution. To decrease prices of industrially produced silicon-based solar cells, the new low-cost production processes are necessary. The main components of most popular silicon solar cells are with diffused emitter layer, passivation, anti-reflective layers and metal electrodes. This type of cells is prepared usually using phosphorus oxychloride diffusion source and metal pastes for screen printing. The diffusion process in diffusion furnace with quartz tube is slow, complicated and requires expensive equipment. The alternative for this technology is very fast in-line processing using the belt furnaces as an equipment. This approach requires different dopant sources. Design/methodology/approach In this work, the diffusion processes were made for two different types of dopant sources. The first one was the commercial available dopant paste from Filmtronics and the second one was the original prepared liquid dopant solution. The investigation was focused on dopant sources fabrication and diffusion processes. The doping solution was made in two stages. In the first stage, a base solution (without dopants) was made: dropwise deionized (DI) water and ethyl alcohol were added to a solution consisting of tetraethoxysilane (TEOS) and 99.8 per cent ethyl alcohol. Next, to the base solution, orthophosphoric acid dissolved in ethyl alcohol was added. Findings Diffused emitter layers with sheet resistance around 60 Ω/sq were produced on solar grade monocrystalline silicon wafers using two types of dopant sources. Originality/value In this work, the diffusion processes were made for two different types of dopant sources. The first one was the commercial available dopant paste from Filmtronics and the second one was the original prepared liquid dopant solution.
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Watanabe, Go, Akane Yamazaki, and Jun Yoshida. "The Missing Relationship between the Miscibility of Chiral Dopants and the Microscopic Dynamics of Solvent Liquid Crystals: A Molecular Dynamics Study." Symmetry 15, no. 5 (2023): 1092. http://dx.doi.org/10.3390/sym15051092.
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Nematic liquid crystals (LCs) are known to undergo a phase transition to chiral nematic LCs possessing helices upon doping with enantiomeric molecules known as chiral dopants. The relationship between the helical pitch (p), the molar fraction (x), and the power of the chiral dopant to induce a helix in a nematic solvent (βM) is expressed as p=1/(x·βM). The helical pitch is easily controlled by the concentration of the chiral dopant when the dopant molecule is miscible with the host nematic LC. However, it has not yet been clarified what the miscibility of the chiral dopant molecules with the nematic LCs depends. Therefore, we performed all-atom molecular dynamics (MD) simulations for the system composed of both Δ and Λ isomers of a chiral dopant molecule dispersed in a nematic LC and investigated the relationship between the microdynamics of the chiral molecules and their miscibility with the nematic solvent. The miscibility of the chiral dopant molecules with the LC solvent was found to correlate with the diffusion coefficient of the LC solvent. In the system where the chiral dopant molecules with high miscibility were added, the diffusion coefficient of the LC solvents was comparable to that of the system in which the chiral molecule was not doped. Furthermore, it was confirmed that more elongated chiral dopants were more miscible with the nematic solvent consisting of calamitic molecules, and that these dopant molecules did not have a significant effect on the diffusion behavior of the LC molecules.
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Pennycook, S. J., R. J. Culbertson, and J. Narayan. "Formation of stable dopant interstitials during ion implantation of silicon." Journal of Materials Research 1, no. 3 (1986): 476–92. http://dx.doi.org/10.1557/jmr.1986.0476.
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High concentrations of self-interstitials are trapped by dopant atoms during ion implantation into Si. For group V dopants, these complexes are sufficiently stable to survive solid-phase-epitaxial (SPE) growth but break up on subsequent thermal processing and cause a transientenhanced diffusion. Dopant diffusion coefficients are enhanced by up to five orders of magnitude over tracer values and are characterized by an activation energy of approximately one half of the tracer values. In the case of group III dopants, any complexes formed during implantation do not survive SPE growth but a second source of self-interstitials becomes significant and leads to similar transient effects. This is the damaged layer underlying the original amorphous/crystalline interface. These observations provide direct evidence for longrange self-interstitial migration in Si, and we believe these are the first observations of the interstitialcy diffusion mechanism with no vacancy contribution. We propose that the complexes are simply interstitial dopant atoms (in a split <100> interstitialcy configuration) that are particularly stable in the case of group V dopants. As they decay self-interstitials are released and cause the transient-enhanced diffusion.
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Pawlik, Grzegorz, and Antoni C. Mitus. "Anomalous Diffusion and Decay of Clusters of Dopants in Lanthanide-Doped Nanocrystals." Materials 18, no. 4 (2025): 815. https://doi.org/10.3390/ma18040815.
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Upconversion (UC) luminescence in doped lanthanide nanocrystals is associated with the energy migration (EM) process within clusters of dopant ions. The process of the synthesis of core–shell nanocrystals occurs at elevated temperatures, promoting the diffusion of the dopants into the shell accompanied by the decay of dopant clusters. The details of this unwanted effect are poorly understood. In this paper, we theoretically study a model of the diffusion of dopant ions in a nanocrystal using Monte Carlo (MC) simulations. We characterize the diffusion, spatial neighboring relations and clustering of dopant ions regarding the function of reduced temperature and MC time of the heating process. The dopants undergo a weak subdiffusion caused by trapping effects. The main results of this study are as follows: (i) the phase diagram of the variables reduced the temperature and MC time, which separates the enhanced and limited cluster-driven EM regimes, and (ii) a dependence of the average nearest distance between Yb ions as a function of reduced temperature, the concentration of Yb ions and MC time was found. In both cases, the requirements for an effective EM are formulated.
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PANKRATOV, E. L. "INFLUENCE OF MECHANICAL STRESS IN A MULTILAYER STRUCTURE ON SPATIAL DISTRIBUTION OF DOPANTS IN IMPLANTED-JUNCTION AND DIFFUSION-JUNCTION RECTIFIERS." Modern Physics Letters B 24, no. 09 (2010): 867–95. http://dx.doi.org/10.1142/s0217984910022925.
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The influence of mechanical stress in a multilayer structure on spatial distribution of dopants in implanted-junction and diffusion-junction rectifiers, which was produced in the structure has been analyzed. It is shown that the stress leads to additional reduction of spatial dimensions of the p–n junction in comparison with the reduction — a result of inhomogeneity — of the diffusion coefficient of dopant and other parameters of dopant redistribution (see, for example, Refs. 1–3).
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Pankratov, Evgeny L., and Elena A. Bulaeva. "Optimization of spatial dependence of diffusion coefficient for acceleration of dopant diffusion." Multidiscipline Modeling in Materials and Structures 12, no. 4 (2016): 672–77. http://dx.doi.org/10.1108/mmms-06-2016-0026.
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Purpose It has been recently shown that diffusion of dopant during doping of inhomogeneous structure could be accelerated or decelerated in comparison with diffusion of dopant in structure with averaged diffusion coefficient. As a continuation of previous work, the purpose of this paper is to introduce an approach of estimating the limited value of acceleration of the dopant diffusion by choosing the dependence of the dopant diffusion coefficient on the coordinates. Design/methodology/approach The authors analyzed relaxation of concentration of dopant during diffusion in inhomogeneous material. The authors determine conditions for maximal acceleration and deceleration of diffusion of dopant. The authors introduced analytical approach for analysis of dopant diffusion in inhomogeneous material. Findings The authors determine conditions for maximal acceleration and deceleration of diffusion of dopant. Originality/value It has been shown that dopant diffusion could be decelerated essentially to a greater extent, rather than accelerated.
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Sueoka, Koji, Ken Kamimura, and Seiji Shiba. "Systematic Investigation of Gettering Effects on 4th Row Element Impurities in Si by Dopant Atoms." Advances in Materials Science and Engineering 2009 (2009): 1–3. http://dx.doi.org/10.1155/2009/309209.
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The gettering of 4th row element impurities (K, Ca, 3d transition metals, and Zn) in Si crystals by dopant atoms was systematically investigated by first-principles calculation through evaluation of the diffusion barrier and the binding energy. The dopant atoms considered include p-type dopants (B), n-type dopants (P, As, Sb), or light elements (C, O). It was found that (1) the diffusion barrier of impurity atoms decreases with an increase in their atomic number up to Ni, (2) B atom becomes an efficient gettering center for metals except for Ni, (3) most of the metals except for Fe and Co cannot be gettered by n-type dopants, and (4) C and O atoms alone do not become efficient gettering centers for the metals used in actual LSI processes. The vacancy and n-type dopant complexes (P, As, Sb) can be efficient gettering centers for Cu in n/n+ epitaxial wafers.
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An, Dao Khac. "Important Features of Anomalous Single-Dopant Diffusion and Simultaneous Diffusion of Multi-Dopants and Point Defects in Semiconductors." Defect and Diffusion Forum 268 (November 2007): 15–36. http://dx.doi.org/10.4028/www.scientific.net/ddf.268.15.
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This paper summarizes some of the main results obtained concerning aspects of anomalous single-dopant diffusion and the simultaneous diffusion of multi-diffusion species in semiconductors. Some important explanations of theoretical/practical aspects have been investigated, such as anomalous phenomena, general diffusivity expressions, general non-linear diffusion equations, modified Arrhenius equations and lowered activation energy have been offered in the case of the anomalous fast diffusion for single-dopant diffusion process. Indeed, a single diffusion process is always a complex system involving many interacting factors; conventional diffusion theory could not be applied to its investigation. The author has also investigated a system of multi-diffusion species with mutual interactions between them. More concretely, irreversible thermodynamics theory was used to investigate the simultaneous diffusion of dopants (As, B) and point defects (V, I) in Si semiconductors. Some attempts at theory development were made, such as setting up a system of general diffusion equations for the simultaneous diffusion of multi-diffusion species involving mutual interactions between them, such as the pair association and disassociation mechanisms which predominated during the simultaneous diffusion of dopants and point defects. The paper then gives some primary results of the numerical solution of distributions of dopants (B, As) and point defects (V, I) in Si semiconductor, using irreversible thermodynamics theory. Finally, several applications of simultaneous diffusion to semiconductor technology devices are also offered.
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Kim, Jongseob, and Ki-Ha Hong. "Retarded dopant diffusion by moderated dopant–dopant interactions in Si nanowires." Physical Chemistry Chemical Physics 17, no. 3 (2015): 1575–79. http://dx.doi.org/10.1039/c4cp04513k.
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Tian, Tang Yi, and Khatijah Aisha Yaacob. "Investigation of Phosphorus Spin on Dopant on SOI Wafer." Applied Mechanics and Materials 918 (January 9, 2024): 75–81. http://dx.doi.org/10.4028/p-3siuhr.
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Silicon on insulator (SOI) wafer has allowed the integrated circuit (IC) industry to create superior, high-performance solutions. In addition, doping techniques are vital in the silicon sector due to the need to regulate the material electrical properties. The spin on dopant (SOD) approach is an alternative method that involves spinning a solution containing dopant onto SOI wafers. This research aims to determine the impact of thermal diffusion temperature and soaking time on sheet resistance of doped SOI wafer using SOD approach. Additionally, the homogeneity of doping was studied by utilizing mapping techniques. Three inches boron-doped SOI wafers were cut and cleaned according to Radio Corporation of America (RCA) standards. N-type dopants of Filmtronics SOD P509 were deposited on SOI wafer by using a spin coater, for 40 seconds at 4,000 revolutions per minute (rpm). The thermal diffusion temperature and soaking time were set between 700°C to 1000°C for 30 to 120 minutes. After thermal diffusion, hydrofluoric acids (HF) were diluted and used to etch samples. All materials were evaluated using a four-point probe, Hall Effect and Atomic Force Microscope (AFM). The results show that when the thermal diffusion soaking time increases, sheet resistance decreases until activated dopants are saturated. When sheet resistance decreases, dopant concentration rises. Temperature and soaking time increase carrier density and surface roughness, while decreasing Hall mobility. From mapping techniques, it shows low non-uniformity value which less than 10% suggests good thermal diffusion control.
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Cowern, Nicholas, and Conor Rafferty. "Enhanced Diffusion in Silicon Processing." MRS Bulletin 25, no. 6 (2000): 39–44. http://dx.doi.org/10.1557/mrs2000.97.
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Semiconductor-grade silicon is one of the most perfect crystalline materials that can be fabricated. It contains less than 1 ppb of unintended impurities and negligible twins or dislocations. Dopants can diffuse in this near-ideal crystal only by interacting with atomic-scale point defects: interstitial atoms or vacancies. These defects migrate through the silicon lattice, occasionally binding with a dopant atom and displacing it by one or more lattice positions.
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Kuganathan, Navaratnarajah, Sashikesh Ganeshalingam, and Alexander Chroneos. "Defects, Diffusion, and Dopants in Li2Ti6O13: Atomistic Simulation Study." Materials 12, no. 18 (2019): 2851. http://dx.doi.org/10.3390/ma12182851.
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In this study, force field-based simulations are employed to examine the defects in Li-ion diffusion pathways together with activation energies and a solution of dopants in Li2Ti6O13. The lowest defect energy process is found to be the Li Frenkel (0.66 eV/defect), inferring that this defect process is most likely to occur. This study further identifies that cation exchange (Li–Ti) disorder is the second lowest defect energy process. Long-range diffusion of Li-ion is observed in the bc-plane with activation energy of 0.25 eV, inferring that Li ions move fast in this material. The most promising trivalent dopant at the Ti site is Co3+, which would create more Li interstitials in the lattice required for high capacity. The favorable isovalent dopant is the Ge4+ at the Ti site, which may alter the mechanical property of this material. The electronic structures of the favorable dopants are analyzed using density functional theory (DFT) calculations.
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Gösele, Ulrich M., and Teh Y. Tan. "Point Defects and Diffusion in Semiconductors." MRS Bulletin 16, no. 11 (1991): 42–46. http://dx.doi.org/10.1557/s0883769400055512.
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Semiconductor devices generally contain n- and p-doped regions. Doping is accomplished by incorporating certain impurity atoms that are substitutionally dissolved on lattice sites of the semiconductor crystal. In defect terminology, dopant atoms constitute extrinsic point defects. In this sense, the whole semiconductor industry is based on controlled introduction of specific point defects. This article addresses intrinsic point defects, ones that come from the native crystal. These defects govern the diffusion processes of dopants in semiconductors. Diffusion is the most basic process associated with the introduction of dopants into semiconductors. Since silicon and gallium arsenide are the most widely used semiconductors for microelectronic and optoelectronic device applications, this article will concentrate on these two materials and comment only briefly on other semiconductors.A main technological driving force for dealing with intrinsic point defects stems from the necessity to simulate dopant diffusion processes accurately. Intrinsic point defects also play a role in critical integrated circuit fabrication processes such as ion-implantation or surface oxidation. In these processes, as well as during crystal growth, intrinsic point defects may agglomerate and negatively impact the performance of electronic or photovoltaic devices. If properly controlled, point defects and their agglomerates may also be used to accomplish positive goals such as enhancing device performance or processing yield.
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An, Dao Khac, Phan Ahn Tuan, Vu Ba Dung, and Nguyen Van Truong. "On the Atomistic Dynamic Modelling of Simultaneous Diffusion of Dopant and Point Defect (B, V, I) in Silicon Material." Defect and Diffusion Forum 258-260 (October 2006): 32–38. http://dx.doi.org/10.4028/www.scientific.net/ddf.258-260.32.
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Understanding the atomic movements of simultanous diffusion of dopant (B) and point defects (V, I) in silicon is of great importance for both experimental and theoretical diffusion studies. This paper presents the atomistic dynamic diffusion modelling of boron (B), self-interstitial (I) and vacancy (V) process in silicon based on simultaneous diffusion of boron dopant and point defects based on a previous developed theory. The simulation is based on the random walk theory with three main diffusion mechanisms: namely vacancy, interstitial and interstitialcy mechanism. The migration frequencies of dopant and point defects have been programmed based on the experimental diffusion data of boron, vacancy and Si self-interstitial. This simulation procedure can be seen very clearly about the atomic movements, the interactions between dopant and point defects via three diffusion mechanisms. The diffusion depth of B, V, I in very short time can be estimated from the simulation picture on the screen. The simulation results reflect the simultaneous diffusion as well as the interaction of boron and point defects via the three diffusion mechanisms. The point defects (V, I) were generated during the dopant diffusion and they diffused further into the depth as shown in the results of the simulation as well as in the previous published experimental findings.
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Pankratov, Evgeniy. "Relaxation time of dopant concentration in inhomogeneous medium with time-varying diffusion coefficient." Izvestiya VUZ. Applied Nonlinear Dynamics 12, no. 3 (2004): 35–44. http://dx.doi.org/10.18500/0869-6632-2004-12-3-35-44.
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In this paper the dynamics of dopant diffusion in an inhomogeneous medium with time-varying diffusion coefficient is analyzed. The conditions on spatial and temporal varying of diffusion coefficient, which correspond to maximal acceleration and deceleration of dopant diffusion time, have been determined.
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Richter, Grant, Allen Knepper, Paul J. Molino, and Timothy W. Hanks. "Chemically Triggered Dopant Release from Surface-Modified Polypyrrole Films." Surfaces 8, no. 2 (2025): 23. https://doi.org/10.3390/surfaces8020023.
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Polypyrrole (PPy) is cationic in its conducting form, requiring a charge-balancing counterion, or dopant. The release of bioactive dopants, driven by the reduction of PPy films, offers a route to controlled drug delivery. Thiol-terminated long chain poly (ethylene glycol) (PEG) reacts with a dodecylbenzene sulfonate (DBSA)-doped PPy, forming a dense overlayer and partially liberating DBSA via the chemical reduction of the film. The resulting PEG brush acts as a barrier to dopant diffusion from the film, but proteins have been shown to disrupt this layer, releasing the DBSA. The mechanism by which this disruption occurs has not been thoroughly investigated. In this study, dopant release from PEG-PPy composites was examined via systematic exposure to a variety of chemical stimuli, including macromolecules such as poly (ethylene imine), polyethylene glycol, and poloxamers, as well as small-molecular-weight alcohols, carboxylic acids, and amines. Dopant release was quantified by quartz crystal microbalance. Poly (ethylene imine) efficiently released DBSA, while anionic and uncharged macromolecules did not. All classes of small molecules triggered dopant release, with longer homologues magnifying the response. The mechanisms of dopant removal are dependent on the functional groups of the stimulating agent and include ion exchange and nucleophilic reduction of the polycationic backbone. Tosylate, salicylate, and penicillin dopants showed release behaviors similar to DBSA, demonstrating the generality of the PEG barrier.
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Haberfehlner, Georg, Matthew J. Smith, Juan-Carlos Idrobo, et al. "Selenium Segregation in Femtosecond-Laser Hyperdoped Silicon Revealed by Electron Tomography." Microscopy and Microanalysis 19, no. 3 (2013): 716–25. http://dx.doi.org/10.1017/s1431927613000342.
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AbstractDoping of silicon with chalcogens (S, Se, Te) by femtosecond laser irradiation to concentrations well above the solubility limit leads to near-unity optical absorptance in the visible and infrared (IR) range and is a promising route toward silicon-based IR optoelectronics. However, open questions remain about the nature of the IR absorptance and in particular about the impact of the dopant distribution and possible role of dopant diffusion. Here we use electron tomography using a high-angle annular dark-field (HAADF) detector in a scanning transmission electron microscope (STEM) to extract information about the three-dimensional distribution of selenium dopants in silicon and correlate these findings with the optical properties of selenium-doped silicon. We quantify the tomography results to extract information about the size distribution and density of selenium precipitates. Our results show correlation between nanoscale distribution of dopants and the observed sub-band gap optical absorptance and demonstrate the feasibility of HAADF-STEM tomography for the investigation of dopant distribution in highly-doped semiconductors.
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Rucker, Holger, Bernd Heinemann, Rainer Kurps, and Yuji Yamamoto. "Dopant Diffusion in SiGeC Alloys." ECS Transactions 3, no. 7 (2019): 1069–75. http://dx.doi.org/10.1149/1.2355901.
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Filipowski, Wojciech. "Model of phosphorus diffusion in silicon for highly doped solar cell emitter layer." Microelectronics International 36, no. 3 (2019): 104–8. http://dx.doi.org/10.1108/mi-12-2018-0079.
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Purpose The purpose of this paper was the development of a model enabling precise determination of phosphorus concentration profile in the emitter layer of a silicon solar cell on the basis of diffusion doping process duration and temperature. Fick’s second law, which is fundamental for describing the diffusion process, was assumed as the basis for the model. Design/methodology/approach To establish a theoretical model of the process of phosphorus diffusion in silicon, real concentration profiles measured using the secondary ion mass spectrometry (SIMS) method were used. Samples with the phosphorus dopant source applied onto monocrystalline silicon surface were placed in the heat zone of the open quartz tube furnace, where the diffusion process took place in the temperature of 880°C-940°C. The measured real concentration profiles of these samples became template profiles for the model in development. Findings The model was developed based on phenomena described in the literature, such as the influence of the electric field of dopant ionized atoms and the influence of dopant atom concentration nearing the maximum concentration on the value of diffusion coefficient. It was proposed to divide the diffusion area into low and high dopant concentration region. Originality/value A model has been established which enabled obtaining a high level of consistency between the phosphorus concentration profile developed theoretically and the real profile measured using the SIMS method. A coefficient of diffusion of phosphorus in silicon dependent on dopant concentration was calculated. Additionally, a function describing the boundary between the low and high dopant concentration regions was determined.
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Stanis, C., O. Thomas, J. Cotte, A. Charai, F. K. LeGoues, and F. M. d’Heurle. "Dopant diffusion in silicides: Effect of diffusion paths." Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films 10, no. 4 (1992): 907–11. http://dx.doi.org/10.1116/1.577693.
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Wolf, Herbert, F. Wagner, J. Kronenberg, and Th Wichert. "On the Formation of Unusual Diffusion Profiles in CdxZn1-xTe Crystals after Implantation of Different Elements." Defect and Diffusion Forum 289-292 (April 2009): 587–92. http://dx.doi.org/10.4028/www.scientific.net/ddf.289-292.587.
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It is known that the diffusion of Ag and Cu in Cd1 xZnxTe crystals exhibits unusual concentration profiles depending strongly on the external vapor pressure of Cd during diffusion. Recent experiments show that the dopant Na forms qualitatively the same diffusion profiles including the phenomenon of uphill diffusion. Also the transition elements Ni and Co show a strong dependence of the diffusion behavior on the external Cd pressure, but the shapes of the concentration profiles differ significantly from those known for Ag and Cu. The different behavior of Ag, Cu, and Na, on the one hand, and Ni and Co, on the other hand, are proposed to be connected to the respective charge states of the dopants at interstitial positions in Cd1 xZnxTe. For the dopants K and Au, unusual diffusion properties have not been observed. The respective diffusion coefficients are DK = 1.2(2)•10 10 cm2/s (750 K) and DAu = 8(2)•10 8 cm2/s (800 K).
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Chumakova, Natalia A., Elena N. Golubeva, Sergei V. Kuzin, et al. "New Insight into the Mechanism of Drug Release from Poly(d,l-lactide) Film by Electron Paramagnetic Resonance." Polymers 12, no. 12 (2020): 3046. http://dx.doi.org/10.3390/polym12123046.
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A novel approach based on convolution of the electron paramagnetic resonance (EPR) spectra was used for quantitative study of the release kinetics of paramagnetic dopants from poly(d,l-lactide) films. A non-monotonic dependence of the release rate on time was reliably recorded. The release regularities were compared with the dynamics of polymer structure changes determined by EPR, SEM, and optic microscopy. The data obtained allow for the conclusion that the main factor governing dopant release is the formation of pores connected with the surface. In contrast, the contribution of the dopant diffusion through the polymer matrix is negligible. The dopant release can be divided into two phases: release through surface pores, which are partially closed with time, and release through pores initially formed inside the polymer matrix due to autocatalytic hydrolysis of the polymer and gradually connected to the surface of the sample. For some time, these processes co-occur. The mathematical model of the release kinetics based on pore formation is presented, describing the kinetics of release of various dopants from the polymer films of different thicknesses.
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Filipowski, Wojciech, Kazimierz Drabczyk, Edyta Wróbel, Piotr Sobik, Krzysztof Waczynski, and Natalia Waczynska-Niemiec. "Borosilicate spray-on glass solutions for fabrication silicon solar cell back surface field." Microelectronics International 35, no. 3 (2018): 172–76. http://dx.doi.org/10.1108/mi-12-2017-0075.
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Purpose The purpose of this paper is to develop a method of preparing spray-on dopant solutions that enable obtaining a p+ region forming a back-surface field (BSF) during the diffusion doping process. The spray-on method used allows to decrease the costs of dopant solution application, which is particularly significant for new low-cost production processes. Design/methodology/approach This paper presents steps of production of high concentration boron dopant solutions enabling diffusion doping of crystalline p-type silicon surfaces. To check the fabricated dopant solutions for stability and suitability for spray-on application, their viscosity and density were measured in week-long intervals. The dopant solutions described in this paper were used in a series of diffusion doping processes to confirm their suitability for BSF production. Findings A method of preparing dopant solutions with parameters enabling depositing them on silicon wafers by the spray-on method has been established. Due to hygroscopic properties of the researched dopant solutions, a maximum surrounding atmosphere humidity has been established. The solutions should not be applied by the spray-on method, if this humidity value is exceeded. The conducted derivatographic examination enabled establishing optimal drying conditions. Originality/value The paper presents a new composition of a dopant solution which contains high concentration of boron and may be applied by the spray-on method. Derivatographic examination results, as well as equations describing the relation between dopant solution density and viscosity and storage time are also original for this research. The established dependencies between the sheet resistance of the fabricated BSF and the diffusion doping time are other new elements described in the paper.
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Taiwo, Rasheed Ayinde, Yeongil Son, Joonghan Shin, and Yusuff Adeyemi Salawu. "Enhanced Activation in Phosphorous-Doped Silicon via Dual-Beam Laser Annealing." Materials 17, no. 17 (2024): 4316. http://dx.doi.org/10.3390/ma17174316.
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In this study, we conduct a comparative analysis of single-beam laser annealing (SBLA) and dual-beam laser annealing (DBLA) techniques for semiconductor manufacturing. In the DBLA approach, two laser beams were precisely aligned to simultaneously heat a phosphorus-doped silicon (Si) wafer. The main objective was to investigate the impact of the two annealing techniques on the electrical properties, crystalline structure, and diffusion profile of the treated phosphorus-doped Si at equivalent laser powers. Both SBLA and DBLA improved the electrical properties of the phosphorus-doped Si, evidenced by increased carrier concentration and reduced carrier mobility. Additionally, the crystalline structure of the phosphorus-doped Si showed favorable modifications, with no defects and improved crystallinity. While both SBLA and DBLA produced similar phosphorus profiles with no significant redistribution of dopants compared to the as-implanted sample, DBLA achieved a higher activation ratio than SBLA. Although the results suggest improved dopant activation with minimal diffusion, further studies are needed to clearly confirm the effect of DBLA on dopant activation and diffusion.
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Portavoce, Alain, Isabelle Berbezier, Antoine Ronda, et al. "Dopant Diffusion in Si1-xGex Thin Films: Effect of Epitaxial Stress." Defect and Diffusion Forum 249 (January 2006): 135–42. http://dx.doi.org/10.4028/www.scientific.net/ddf.249.135.
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We have investigated the lattice diffusion of B and Sb by means of molecular beam epitaxy in Si1−xGex (x < 0.2) layers grown on Si(001) substrate. Using Si1−xGex relaxed buffers we were able to differentiate the chemical effect (change in the Ge composition) as opposite to the biaxial stress effect (due to the epitaxy on Si) on dopant diffusion. B diffusion follows a behavior opposite to Sb diffusion versus Ge composition and biaxial stress. These results are explained in view of the difference of diffusion mechanism between B (interstitials) and Sb (vacancies). We also show that dopant diffusion follows contrasting behaviors under biaxial pressure and hydrostatic pressure, and that the activation volume of dopant diffusion is of opposite sign for biaxial pressure and for hydrostatic pressure. This is explained using a formalism based on the extra work done by the system for diffusion under pressure, concluding that for biaxial stress the activation volume depends mainly on the relaxation volume linked to the defect formation.
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Ma, N., and J. S. Walker. "A Model of Dopant Transport During Bridgman Crystal Growth With Magnetically Damped Buoyant Convection." Journal of Heat Transfer 122, no. 1 (1999): 159–64. http://dx.doi.org/10.1115/1.521446.
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This paper presents a model for the unsteady transport of a dopant during the vertical Bridgman crystal growth process with a planar crystal-melt interface and with an externally applied axial magnetic field. This dilute mass transport depends on the convective and diffusive mass transport of the dopant. The convective mass transport is driven by buoyant convection in the melt, which produces nonuniformities in the concentration in both the melt and the crystal. This convective transport is significant even for a strong magnetic field Bo=2 T. However, the electromagnetic damping of the melt motion produces a local region adjacent to the crystal-melt interface which is dominated by diffusion. Thus, this melt solidifies with a relatively radially uniform concentration, so that the radial distribution of dopants in the crystal is also relatively radially uniform. The transient model predicts the dopant distribution in the entire crystal. [S0022-1481(00)02301-X]
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Nilsson, Johan O., Mikael Leetmaa, Olga Yu Vekilova, Sergei I. Simak, and Natalia V. Skorodumova. "Oxygen diffusion in ceria doped with rare-earth elements." Physical Chemistry Chemical Physics 19, no. 21 (2017): 13723–30. http://dx.doi.org/10.1039/c6cp06460d.
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Law, M. E., H. Park, and P. Novell. "Theory of dopant diffusion assuming nondilute concentrations of dopant‐defect pairs." Applied Physics Letters 59, no. 26 (1991): 3488–89. http://dx.doi.org/10.1063/1.105662.
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Dissanayake, Sashini Senali, Nicole O. Pallat, Philippe K. Chow, et al. "Carrier lifetimes in gold–hyperdoped silicon—Influence of dopant incorporation methods and concentration profiles." APL Materials 10, no. 11 (2022): 111106. http://dx.doi.org/10.1063/5.0126461.
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Incorporating ultrahigh concentrations of deep-level dopants in silicon drastically alters silicon’s optoelectronic properties. Photodiodes built from silicon hyperdoped with gold extend light sensitivity into the shortwave infrared region, far beyond the absorption edge of a pristine silicon sample. Deep-level dopants, however, also enhance carrier recombination; even though hyperdoped silicon has great light absorption properties, short charge carrier lifetime limits its applications. In this work, using terahertz spectroscopy, we investigate the charge carrier lifetime of gold–hyperdoped silicon, where the gold dopants are introduced by either film deposition or ion implantation, followed by pulsed laser melting. Using reactive ion etching, we measure how carrier lifetime changes when dopant concentration profiles are altered. Furthermore, using a 1D diffusion and recombination model, we simulate carrier dynamics when electrons are excited by sub-bandgap light. Our results show that the dopant distribution profile heavily influences excited carrier dynamics. We found that etching improves the half-life by a factor of two. In the short-wave-infrared range, the gold dopants are both light absorption centers and recombination centers. Focusing on optoelectronic properties in the short-wave-infrared region, our results suggest that these samples are over doped—etching much of the gold dopants away has little impact on the number of excited electrons at a later time. Our results suggest that dopant profile engineering is important for building efficient optoelectronic devices using hyperdoped semiconductors.
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Jäger, Wolfgang. "Diffusion and Defect Phenomena in III-V Semiconductors and their Investigation by Transmission Electron Microscopy." Diffusion Foundations 17 (July 2018): 29–68. http://dx.doi.org/10.4028/www.scientific.net/df.17.29.
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This article reviews the studies of diffusion and defect phenomena induced by high-concentration zinc diffusion in the single-crystal III-V compound semiconductors GaAs, GaP, GaSb and InP by methods of transmission electron microscopy and their consequences for numerical modelling of Zn (and Cd) diffusion concentration profiles. Zinc diffusion from the vapour phase into single-crystal wafers has been chosen as a model case for interstitial-substitutional dopant diffusion in these studies. The characteristics of the formation of diffusion-induced extended defects and of the temporal evolution of the defect microstructure correlate with the experimentally determined Zn profiles whose shapes depend on the chosen diffusion conditions. General phenomena observed for all semiconductors are the formation of dislocation loops, precipitates, voids, and dislocations and of Zn-rich precipitates in the diffusion regions. The formation of extended defects near the diffusion front can be explained as result of point defect supersaturations generated by interstitial-substitutional zinc exchange via the kick-out mechanism. The defects may act as sinks for dopants and as sources and sinks for point defects during the continuing diffusion process, thereby providing a path to establishing defect-mediated local point defect equilibria. The investigations established a consistent picture of the formation and temporal evolution of defects and the mechanisms of zinc diffusion in these semiconductors for diffusion conditions leading to high-concentration Zn concentrations. Based on these results, numerical modelling of anomalously shaped dopant concentration profiles leads to satisfactory quantitative results and yields information on type and charge states of the point defect species involved, also for near-surface Zn concentration profiles and the absence of extended defects.
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Portavoce, Alain, Roberto Simola, Dominique Mangelinck, Jean Bernardini, and Pascal Fornara. "Dopant Diffusion during Amorphous Silicon Crystallization." Defect and Diffusion Forum 264 (April 2007): 33–38. http://dx.doi.org/10.4028/www.scientific.net/ddf.264.33.
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We have investigated the redistribution of B during the crystallization of an amorphous Si layer homogeneously doped with P. The redistribution of B only occurs for concentrations lower than 2 × 1020 at cm−3. Crystallization leads to a non “Fickian” redistribution, allowing an abrupt interface between the regions doped and undoped with B. Once the crystallization is ended, B diffuses through the layer in the type B regime with a coefficient which is in agreement with the literature data for diffusion in polycrystalline Si. Although the P distribution is homogeneous in the entire layer, for a temperature as high as 755 °C, P diffuses towards the region the most concentrated in B. The B and P interactions are interpreted as chemical interactions.
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Stadler, A., T. Sulima, J. Schulze, et al. "Dopant diffusion during rapid thermal oxidation." Solid-State Electronics 44, no. 5 (2000): 831–35. http://dx.doi.org/10.1016/s0038-1101(99)00287-7.
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Lyytik�inen, K., S. T. Huntington, A. L. G. Carter, et al. "Dopant diffusion during optical fibre drawing." Optics Express 12, no. 6 (2004): 972. http://dx.doi.org/10.1364/opex.12.000972.
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Glitzky, A., and W. Merz. "Single dopant diffusion in semiconductor technology." Mathematical Methods in the Applied Sciences 27, no. 2 (2003): 133–54. http://dx.doi.org/10.1002/mma.447.
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Gribelyuk, Michael A., Sanjay Mehta, Jeffrey B. Johnson, and Lee Kimball. "Two-dimensional dopant potential mapping in a fin field effect transistor by off-axis electron holography." Journal of Applied Physics 132, no. 4 (2022): 045702. http://dx.doi.org/10.1063/5.0091586.
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Progress in the development of nanometer scaled Fin Field Effect Transistor (FinFET) devices is affected by a lack of understanding of relevant dopant diffusion phenomena due to limited experimental data. In particular, 2D dopant potential mapping by electron holography in 3D FinFET devices has been challenged by the overlap of electrically active fins, metal films, and dielectric films in the electron beam direction. This paper presents methodology on how to map dopant potential in modern FinFET devices. A custom-device structure was developed, which preserved all essential features of the device manufacturing process. The dopant reconstruction method is suggested to account for the presence of materials other than silicon fin between fins. A comparison of lateral dopant potential profiles with device simulations offers agreement within 0.32 V. Compositional non-uniformity of materials between fin devices is identified as the main limiting factor. A further reduction of compositional non-uniformity should allow for quantitative 2D dopant potential mapping with high sensitivity to probe the effects of dopant segregation, deactivation, and diffusion kinetics in 3D FinFET devices at the nanometer scale.
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Duggan, Shane P., Hua Yang, Niall P. Kelly та ін. "P‐substrate InP‐based 1.5 μm lasers using an internal carbon‐doped layer to block p‐dopant diffusion". Microwave and Optical Technology Letters 60, № 10 (2018): 2363–67. http://dx.doi.org/10.1002/mop.31364.
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AbstractP‐substrate AlGaInAs/InP lasers are enabled using an internal carbon‐doped layer to block Zn‐diffusion. These inverted lasers are developed for the aim of further monolithic vertical integration with passive or active material, which would allow full system on‐chip integration. The lasers emit at 1.5 μm making them ideal for telecommunication applications. Different p‐substrate laser designs were grown to quantify the effect the carbon doped layer had on blocking Zn p‐dopants diffusion, which permits the long growths necessary for vertical integration. Current, voltage, and capacitance measurements were used to examine the different laser designs, proving that Zn p‐dopant diffusion is responsible for p‐substrate laser failure.
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Chevallier, Jacques, François Jomard, Cecile Saguy, R. Kalish, and A. Deneuville. "Hydrogen Diffusion Mechanisms and Hydrogen-Dopant Interactions in Diamond." Advances in Science and Technology 46 (October 2006): 63–72. http://dx.doi.org/10.4028/www.scientific.net/ast.46.63.
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Electronic grade diamond is usually grown by Microwave Plasma assisted CVD from a hydrogen rich CH4/H2 mixture, hence hydrogen is likely to be incorporated during growth. It may thus affect the properties of the material. In this work, we present the state of the art on the understanding of the diffusion properties of hydrogen and of the hydrogen-dopant interactions in diamond. First, we show the existence of strong interactions between H and boron dopants in diamond. The formation of H-acceptor pairs results in the passivation of the acceptors. Further, we show that an excess of hydrogen in selected boron-doped diamond epitaxial layers can result in the creation of H and boron-containing donors with a ionization energy of 0.36 eV (about half the ionization energy of phosphorus). At 300 K, the n-type conductivity of hydrogenated borondoped diamond is several orders of magnitude higher than the conductivity of phosphorus-doped diamond. The formation process of these new donors is discussed.
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Bracht, Hartmut. "Diffusion and defect reactions in isotopically controlled semiconductors." Diffusion Fundamentals 8 (July 1, 2008). http://dx.doi.org/10.62721/diffusion-fundamentals.8.161.
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Point defects in semiconductors play a decisive role for the functionality of semiconductors. A detailed, quantitative understanding of diffusion and defect reactions of dopants is required for advanced modelling of modern nanometer size electronic devices. With isotope heterostructures which consist of epitaxial layers of isotopically pure and deliberately mixed stable isotopes, we have studied the simultaneous self- and dopant diffusion in several major semiconductors such as silicon and germanium. Detailed analysis of the simultaneous diffusion of self- and dopant atoms in Si and Ge yields information about the ionization levels of native defects and about dopant-defect interactions in Si and Ge. The results of these diffusion studies are highlighted in this work.
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Liu, Chun-Li. "Screening Beneficial Dopants to Cu Interconnect by Modeling." MRS Proceedings 677 (2001). http://dx.doi.org/10.1557/proc-677-aa7.13.
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Cu is currently being used as the new generation of advanced interconnects. Beneficial additives or dopants to Cu have been sought to improve the electromigration performance of the Cu interconnects primarily through experimental approaches [1]. As a vital alternative, we have established a virtual simulation procedure to screen the potential dopants to Cu by modeling. There are many factors such as film density, stress, stress- voiding, grain boundary defect / diffusion, interface adhesion / defect / diffusion, grain structures (texture, grain size and size distribution) and so on that can affect the electromigration. Here we assume that Cu diffusion along the grain boundaries (GBs) is the dominant mechanism that is responsible for the electromigration performance of the Cu interconnects. As schematically shown in Fig.1, if a dopant is added to Cu, most of the dopant will reside in bulk initially. In order for the dopant to play a beneficial role, it has to be able to segregate to the grain boundary. Then, the dopant is supposed to slow down Cu diffusion along the grain boundary and this can be achieved if the dopant can increase the overall activation energy of Cu grain boundary diffusion.
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Ural, Ant, Serene Koh, P. B. Griffin, and J. D. Plummer. "What Does Self-Diffusion Tell Us about Ultra Shallow Junctions?" MRS Proceedings 610 (2000). http://dx.doi.org/10.1557/proc-610-b4.11.
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AbstractUnderstanding the coupling between native point defects and dopants at high concentrations in silicon will be key to ultra shallow junction formation in silicon technology. Other effects, such as transient enhanced diffusion (TED) will become less important. In this paper, we first describe how thermodynamic properties of the two native point defects in silicon, namely vacancies and self-interstitials, have been obtained by studying self-diffusion in isotopically enriched structures. We then discuss what this tells us about dopant diffusion. In particular, we show that the diffusion of high concentration shallow dopant profiles is determined by the competition between the flux of mobile dopants and those of the native point defects. These fluxes are proportional to the interstitial or vacancy components of dopant and self-diffusion, respectively. This is why understanding the microscopic mechanisms of silicon self-diffusion is important in predicting and modeling the diffusion of ultra shallow dopant profiles. As an example, we show experimental data and simulation fits of how these coupling effects play a role in the annealing of shallow BF2 ion implantation profiles. We conclude that relatively low temperature furnace cycles following high temperature rapid thermal anneals (RTA) have a significant effect on the minimum junction depth that can be achieved.
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Ohdomari, I., K. Konuma, M. Takano, et al. "Dopant Redistribution During Silicide Formation." MRS Proceedings 54 (1985). http://dx.doi.org/10.1557/proc-54-63.
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ABSTRACTAfter the review of dopant redistribution phenomena observed during formation of near noble metal suicides, we describe the results of our recent experiments to get a better understanding of a mechanism of the dopant redistribution phenomenon in Si substrates. The key factors to understand the dopant redistribution are dopant segregation at the suicide/ Si interface due to lower solubility limit of dopants in suicides, enhanced diffusion of dopants into the Si substrate at much lower temperatures than the ordinary thermal diffusion, and electrical activation of the redistributed dopants. The results of As and carrier concentration measurements before and after Pd2Si formation to make clear the third factor show that the electrical activity of the redistributed As atoms in Si is strongly dependent on the initial activity before Pd2Si formation which is controlled by the temperature for the pre-annealing of As implanted Si.Shrinkage of extrinsic dislocation loops introduced by As implantation and subsequent annealing have been observed after Pd2Si formation, which is a good evidence of vacancy generation during Pd2Si formation. The role of the vacancies and interstitials on the second factor, the enhanced diffusion, has also been discussed. Finally we list a few issues to be answered in future by more detailed works in order to get a complete understanding of the redistribution phenomenon.
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Tischler, M. A., and T. F. Kuech. "Incorporation and Diffusion of P-Type Dopants for Metal Organic Vapor Phase Epitaxy." MRS Proceedings 144 (1988). http://dx.doi.org/10.1557/proc-144-91.
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ABSTRACTThe control of p-type dopants is very important in producing high performance minority carrier devices such as heterojunction bipolar transistors (HBT) and lasers. In this study, an electrical characterization technique is described which is very sensitive to the p-type dopant profile in a heterojunction. Both the placement of the dopant, i.e. the as-grown profile, and thermal diffusion effects have been investigated. The factors which control the initial placement and subsequent diffusion of the dopant species have been determined and used to produce device-quality GaAs/Al0.30Ga0.70As p+/n heterojunctions.
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Deal, M. D., C. J. Hu, C. C. Lee, and H. G. Robinson. "Modeling Dopant Diffusion in Gallium Arsenide." MRS Proceedings 300 (1993). http://dx.doi.org/10.1557/proc-300-365.
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ABSTRACTWe have been developing models for our process simulators, SUPREM 3.5 and SUPREM-IV, for processes used in the fabrication of GaAs devices. Our initial experiments led to relatively simple models for diffusion of common dopants in GaAs, usually dependent only on temperature and the local dopant or carrier concentration. These models were incorporated into our first GaAs simulator, SUPREM 3.5. While these simple models were adequate for some process conditions, there are many cases where anomalous diffusion occurs and these models break down. The generally accepted diffusion mechanisms for n- and p-type dopants in GaAs have been shown to be the same as, or indistinguishable from, the models used for diffusion in silicon, and are therefore compatible with the diffusion algorithms used in SUPREM-IV. These algorithms include the effects of point defects. GaAs and eight of its dopants have recently been incorporated into SUPREM-IV and we have modeled, or are attempting to model, many of the anomalous diffusion phenomena using this simulator. These phenomena include uphill diffusion of implanted dopants, time dependent diffusion, implant energy dependent diffusion, and abnormal diffusion of grown-in dopants in MBE and MOCVD material.
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Bunea, Marius M., and Scott T. Dunham. "Lattice Monte Carlo Simulations of Vacancy-Mediated Diffusion and Aggregation using Ab-Initio Parameters." MRS Proceedings 469 (1997). http://dx.doi.org/10.1557/proc-469-353.
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The lattice Monte Carlo method with parameters from recent first-principle calculations1,2 are used to investigate dopant diffusion in silicon. In the simulations, vacancy hopping on a silicon lattice is biased by changes in system energy, including interactions up to the sixth-nearest neighbor. We find that vacancy-mediated diffusivity increases dramatically above 1020 cm−3, in agreement with experimental observations3 and previous calculations.4 However, for very long simulation times, arsenic diffusivity is reduced due to formation of AsxV complexes, with clustering more pronounced at high doping levels. As suggested by Ramamoorthy and Pantelides,5 we find that As2V complexes are mobile, and although they diffuse much more slowly than AsV pairs, they appear likely to have a significant role in high concentration diffusion due to their much higher numbers. We also investigated dopant fluxes in a vacancy gradient. For dopants like As for which pair diffusion is limited by the dissociation to third-nearest neighbor distances, the dopant flux is less than that predicted by pair diffusion models, with greater difference at higher temperatures. In contrast, for phosphorus/vacancy pairs, whose diffusion is limited by dopant/vacancy exchange, the dopant flux is close to the predictions of pair diffusion.
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Li, Hong-Jyh, Robin Tichy, Jonathon Ross, Jeff Gelpey, Ben Stotts, and Heather Galloway. "Dopant Diffusion Simulation in Thin-SOI." MRS Proceedings 765 (2003). http://dx.doi.org/10.1557/proc-765-d5.8.
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AbstractAs the top Si layer is thinned, the dopants' diffusion in the confined Si layer in SOI wafer with respect to different thermal treatments needs to be better understood. Boron, BF2 with/without Ge pre-amorphization were implanted into bulk Si and SOI wafers with 530 Å Si and 1475A BOX. Samples were annealed using both spike (Impulse) anneal and Flash anneal. Simulations of dopant diffusion is used to resolve apparent differences in dopant profiles that resulted for SOI in contrast with bulk Si samples. Result suggests that the implantation damage difference between SOI and bulk Si makes the B diffusion in SOI higher than in bulk Si.
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Yang, Yunqi, Dongdong Chen, Di Li, et al. "Research on the Evolution of Defects Initiation and the Diffusion of Dopant on the Si/SiO2 Interface." Advanced Materials Interfaces, October 23, 2024. http://dx.doi.org/10.1002/admi.202400751.
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AbstractSi/SiO2 interfaces, important parts of Si‐based devices, significantly influence the performance of Si‐based devices. However, owing to the impact of the external environment, related defects are generated, and the dopant can diffuse and redistribute, causing a series of parasitic effects that reduce the lifespan of the devices. In this paper, recent investigations on the mechanisms of interface defect initiation and dopant diffusion are systematically reviewed. At the Si/SiO2 interface, Pb‐type center defects are identified, including Pb, Pb0, and Pb1 center defects. Near the interface, E’ center defects are identified, and H‐related defects are also formed. In addition, dopant ions are introduced in the Si/SiO2 interface to improve the conductivity. However, during the oxidation process, the dopant ions can diffuse and redistribute at the interface. Investigations of the dopant diffusion mechanism, modeling, and dopant pile‐up are reviewed in this paper. Comparisons and discussions of the initial mechanism of defects, structures of defects, and dopant diffusion mechanisms are presented to provide valuable guidance for improving the performance and extending the lifespan of Si/SiO2 interfaces. Finally, an outlook is presented, including improving the models of interface defects to better protect against local strains and multienvironment impacts, and developing 3D detection technology for dopants.
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d'Heurle, F. M., A. E. Michel, F. K. LeGoues, G. Scilla, J. T. Wetzel, and P. Gas. "Dopant Diffusion in TiSi2." MRS Proceedings 77 (1986). http://dx.doi.org/10.1557/proc-77-333.
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ABSTRACTDopant elements, B and Ga, P, As and Sb, and Ge as well, have been implanted into thick (350–400 nm) layers of TiSi2 prepared by Ti-Si reaction. Both B and Sb appear to be immobile, this behavior is thought to result from very small solid solubilities, rather than from very small diffusion coefficients. The other elements display about the same behavior, with detectable grain boundary diffusion at temperatures as low as 600°C, and lattice diffusion becoming considerable at 750°C, so that with the cooperation of both phenomena almost complete homogenisation of these relatively thick layers occurs in 30 minutes at 800°C. Germanium is used in lieu of a Si radioactive tracer because it can be analyzed by Secondary Ion Mass Spectroscopy. Its behavior is thought to imply that there is little equilibrium adsorption of the dopant elements at the Si/TiSi2 interface. The comparable values of the diffusion coefficients for the mobile elements confirm the anticipation that the dopants move as substitutional atoms on the Si sublattice. Results obtained with some samples implanted with both dopant and Ti indicate that in these silicon-saturated suicide layers the diffusion process is not significantly affected by small changes in stoichiometry.
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Sawada, Ryohto, Kosuke Nakago, Chikashi Shinagawa, and So Takamoto. "High-throughput investigation of stability and Li diffusion of doped solid electrolytes via neural network potential without configurational knowledge." Scientific Reports 14, no. 1 (2024). http://dx.doi.org/10.1038/s41598-024-62054-7.
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AbstractSolid electrolytes hold substantial promise as vital components of all-solid-state batteries. Enhancing their performance necessitates simultaneous improvements in their stability and lithium conductivity. These properties can be calculated using first-principles simulations, provided that the crystal structure of the material and the diffusion pathway through the material are known. However, solid electrolytes typically incorporate dopants to enhance their properties, necessitating the optimization of the dopant configuration for the simulations. Yet, performing such calculations via the first-principles approach is so costly that existing approaches usually rely on predetermined dopant configurations informed by existing knowledge or are limited to systems doped with only a few atoms. The proposed method enables the optimization of the dopant configuration with the support of neural network potential (NNP). Our approach entails the use of molecular dynamics to analyze the diffusion after the optimization of the dopant configuration. The application of our approach to Li$$_{10}$$ 10 MP$$_{2}$$ 2 S$$_{12-x}$$ 12 - x O$$_{x}$$ x (M = Ge, Si, or Sn) reproduce the experimental results well. Furthermore, analysis of the lithium diffusion pathways suggests that the activation energy of diffusion undergoes a percolation transition. This study demonstrates the effectiveness of NNPs in the systematic exploration of solid electrolytes.