Дисертації з теми "Si Quantum Dot"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-26 дисертацій для дослідження на тему "Si Quantum Dot".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
Surana, Kavita. "Towards silicon quantum dot solar cells : comparing morphological properties and conduction phenomena in Si quantum dot single layers and multilayers." Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00647293.
Повний текст джерелаWang, T. "High-performance III-V quantum-dot lasers monolithically grown on Si and Ge substrates for Si photonics." Thesis, University College London (University of London), 2012. http://discovery.ucl.ac.uk/1362647/.
Повний текст джерелаWigblad, Dan. "Structural and optical characterization of Si/Ge quantum dots." Thesis, Linköping University, The Department of Physics, Chemistry and Biology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-11672.
Повний текст джерелаIn this study silicon-germanium quantum dots grown on silicon have been investigated. The aim of the work was to find quantum dots suitable for use as a thermistor material. The quantum dots were produced at KTH, Stockholm, using a RPCVD reactor that is designed for industrial production.
The techniques used to study the quantum dots were: HRSEM, AFM, HRXRD, FTPL, and Raman spectroscopy. Quantum dots have been produced in single and multilayer structures.
As a result of this work a multilayer structure with 5 layers of quantum dots was produced with a theoretical temperature coefficient of resistance of 4.1 %/K.
Aslan, Bulent. "Physics And Technology Of The Infrared Detection Systems Based On Heterojunctions." Phd thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12604801/index.pdf.
Повний текст джерелаAriyawansa, Gamini. "Semiconductor Quantum Structures for Ultraviolet-to-Infrared Multi-Band Radiation Detection." Digital Archive @ GSU, 2007. http://digitalarchive.gsu.edu/phy_astr_diss/17.
Повний текст джерелаLipps, Ferdinand. "Electron spins in reduced dimensions: ESR spectroscopy on semiconductor heterostructures and spin chain compounds." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-74470.
Повний текст джерелаJames, Daniel. "Fabrication and electrical characterisation of quantum dots : uniform size distributions and the observation of unusual electrical characteristics and metastability." Thesis, University of Manchester, 2010. https://www.research.manchester.ac.uk/portal/en/theses/fabrication-and-electrical-characterisation-of-quantum-dots-uniform-size-distributions-and-the-observation-of-unusual-electrical-characteristics-and-metastability(01bb9182-5290-4ad1-b6a4-3aed3970dbcf).html.
Повний текст джерелаPANTINI, SARA. "Analysis and modelling of leachate and gas generation at landfill sites focused on mechanically-biologically treated waste." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2013. http://hdl.handle.net/2108/203393.
Повний текст джерелаChen, Hung-Bin, and 陳弘斌. "Optical properties of Ge/Si/Ge quantum dot in multilayer structure." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/59065285991693145803.
Повний текст джерела國立中央大學
物理研究所
99
In this paper, we have studied the optical properties of Ge/Si/Ge quantum dots (QDs) structure by using Photoluminescence (PL) spectroscopy.And we use rapid thermal annealing process to improve its light efficiency.Comparing the PL measurements of Ge/Si/Ge QDs structure with Ge/Si QDs structure, the structural difference effect on optical properties is studied. According to the emission energy of annealed samples in excitation-powerdependent PL measurements, we found that Ge/Si/Ge QDs structure has higher emission energy and lower carriers confinement depth due to atomic intermixing effect. According to the PL intensity with power sublinear relation at different temperature measurements, we suggest that the defect has negative effect on light efficiency because emitting light will be absorbed by the electrons confined in the defect. Finally, we found that the Ge/Si/Ge QDs structure has higher activation energy from Temperature-dependent PL measurements. Therefore, we point out that the holes in Ge/Si/Ge QDs structure probably can exist on nearby QDs by tunneling effect.
Kuo, Kuang-Yang, and 郭光揚. "Development of novel Si quantum dot thin films for solar cells application." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/88042976960020575941.
Повний текст джерела國立交通大學
光電工程研究所
102
In order to resolve the critical issues of “Green House Effect” and “Energy Crisis” for humanity’s future, the accelerated developments of renewable energies are necessary. Among all of the renewable energies, solar cells (SCs) are highly considered as the most potential one. To ponder these key factors of efficiency, cost, and lifetime, undoubtedly, the Si-based SCs have the most advantages on popularized developments in the future. However, to successfully achieve high efficiency and low cost, also called the third generation SC, the tandem Si-based SCs with multi-bandgap is required to efficiently reduce the mismatched photon energy loss. Based on the unique properties of Si quantum dot (QD), we propose to develop the novel Si QD thin films by utilizing a gradient Si-rich oxide multilayer (GSRO-ML) structure and integrating with ZnO matrix material to overcome the bottlenecks of the largely limited carrier transport efficiency in the Si-based SCs integrating Si QDs. In the beginning of this dissertation, we talk about the importance and recent developments of SCs, and then, the advantages and challenges of SCs integrating Si QDs are discussed. After that, our motivations, fabrication process, and apparatus are also introduced in details. To achieve the formation of super-high density Si QD thin films, we forsake the traditional [SiO2/SRO]-ML structure and develop a new one, GSRO-ML. In our results, by utilizing the periodical variations in Si/O atomic concentration during deposition, the Si QDs with super-high density and good size control can be self-assembled from the uniform aggregations of Si-rich atoms during annealing. Besides, the considerable enhancements on photovoltaic properties are also obtained by using a GSRO-ML structure due to the improved carrier transport efficiency and larger optical absorption coefficient. To obtain the better carrier transport path for the Si QD thin films, we also develop a new matrix material, ZnO, because it has many desirable features, such as wide and direct bandgap, high transparency, and highly tunable electrical properties. In our results, though embedded with Si QDs, the optical properties of ZnO thin film can be preserved in the long- and short-wavelength ranges. In the middle-wavelength range, the significantly enhanced light absorption and the unusual PL emission peak, owing to embedding Si QDs, are observed. These results represent the sub-bandgap formation in ZnO thin film by utilizing Si QDs while maintaining the essential optical properties of ZnO matrix. In the electrical properties, the Si QD embedded ZnO thin film reveals the significantly higher conductivity than that using SiO2 matrix material. Besides, the carriers transport mainly via ZnO matrix, not through Si QDs, is clearly observed. This unique transport mechanism differing from those using the traditional Si-based dielectric matrix materials has great potential on leading to the much better carrier transport efficiency and electrical properties for SC applications. In this dissertation, we had demonstrated the proposed novel Si QD thin films, utilizing a GSRO-ML structure and integrating with ZnO matrix material, are more suitable and advantageous for the Si-based SCs integrating Si QDs. Therefore, the high-efficiency Si-based SCs integrating Si QDs can be most definitely expected using the novel Si QD thin films.
Wu, Zi-Hao, and 吳梓豪. "Formation of Ge Quantum Dot and Shell for Si on Insulator Applications." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/08688797233761845118.
Повний текст джерела國立中央大學
電機工程學系
102
This thesis continuously studied the formation of Ge QDs using thermal oxidation of poly-SiGe pillar/Si3N4/Si heterostructure in our lab, and further discussed the dependence of morphology and internal defects of Ge QD between oxidation and annealing conditions. Meanwhile, the author used this process on poly-SiGe pillar/ Si3N4/Si on insulator substrate in order to realize Ge/SiO2/Si on insulator heterostructure advantaging in the gate engineering of Ge MOSFET and phototransistor. This thesis used transmission electron microscopy (TEM), energy dispersive X-ray (EDX) mapping and Raman analysis to investigate the evolution of morphology, crystallinity, lattice orientation, defects, Ge concentration and stress of Ge QD and shell under different thermal budget by modifying oxidation and annealing conditions. The author found that Ge QD catalytically enhances the local oxidation of underlying Si3N4 and Si. The released Si atoms diffuse into Ge QD and make the migration of Ge QD in Si3N4 and Si. In addition, the quantity of Si inward Ge QD obviously changes the morphology of Ge QD. This thesis investigated the relationship between Ge QD/shell using selective oxidation and thermal budget. The demonstrated SiGe shell with uniform thickness, subject to compressive stress and stable (111) lattice orientation not only can be used in self-aligned Ge QD but also have good SiO2 quality between Ge QD and shell. Therefore, this heterostructure can be used as the application of gate stack and the channel of Ge MOSFET and phototransistor.
Chen, You-Jheng, and 陳佑政. "Boron Doping Effect on the Super-High Density Si Quantum Dot Thin Films." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/24717970097630577489.
Повний текст джерела國立交通大學
光電工程研究所
102
In order to further reduce quantum dot (QD) separation, we had proposed and successfully developed the gradient Si-rich oxide multilayer (GSRO-ML) structure for the super-high density Si QD thin films with larger carrier tunneling probability. In this study, we investigate the B-doping and QD size effects on the super-high density Si QD thin films by using a GSRO-ML structure. Under B-doping effect, the preserved high crystallinity of Si QDs and the slightly reduced Eg with increasing PB are observed, besides, the electrical and PV properties are enhanced with increasing PB from 0 to 25W due to the increased active B-doped atoms but degraded at the higher PB than 30 W due to the increased inactive B-doped atoms and the interfacial over-diffusion of B-doped atoms. The decreased VOC with increasing PB due to the interfacial over-diffusion is efficiently improved by inserting the lowly B-doped GSRO thin films as buffer layers. Under QD size effect, the red-shift effect is clearly confirmed in the absorption band edge and quantum efficiency response with increasing NL thickness. Therefore, our results had demonstrated the feasibility and great potential for the higher efficiency Si-based solar cells integrating Si QDs by using a GSRO-ML structure.
Chang, Jia-Ruei, and 張家瑞. "Phosphorous Doping Effect on the Super-High Density Si Quantum Dot Thin Films." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/03029864165879316474.
Повний текст джерела國立交通大學
光電工程研究所
103
Recently, the solar cells (SCs) integrating nano-crystalline Si quantum dot (nc-Si QD) thin films have been researched widely due to the highly-tunable ability of bandgap (Eg). Si-QD SCs can overcome the issue for energy loss from the high-energy photon due to the larger Eg than monocrystalline and amorphous Si. The general structure is Si QD embedded in SiO2 matrix utilizing [Si dioxide/Si rich oxide] multilayer ([SiO2/SRO]-ML) thin film structure. However, the poor photovoltaic (PV) properties were obtained due to naturally highly resistive properties of SiO2 matrix. Therefore, the reduction of QD separation, the increasing of QD density and the heavily impurities (B, P atoms, etc.) doping are available methods to enhance PV properties of devices. In 2013, we have proposed a new structure, gradient Si-rich oxide mutilayer (GSRO-ML) structure and demonstrated a super-high density Si QD thin film to reduce the separation between Si QDs which leads to the higher probability of carrier tunneling. To further enhance the PV properties, the boron doping effect on the super-high density Si QD thin film have been studied and the obvious improvement on PV properties can be observed. In this thesis, we propose to dope P atoms into GSRO-ML thin films by means of thermal diffusion of phosphorus oxide trichloride (POCl3). The P-doped effect and the issue of defect reduced of the P-doped super-high density Si QD thin film will be investigated and discussed. Under P-doping effect, the preserved crystallinity of Si QDs and high absorption coefficient are maintained. In addition, the electrical and PV properties are enhanced with increasing POCl3 flow rate from 280 to 880 sccm, and the best performance is obtained at 880 sccm due to the largest active P-doped atoms but decreased at 1000 sccm due to the increased inactive P-doped atoms. However, a harmful material for Si QD thin films, PCl5, was produced during the high temperature P doping process. We raise the O2 flow rate for the PCl5 reacted absolutely. The clear effect of defect reduced is observed, and the declined PV properties of devices have been observed. The phenomenon means the defect in matrix is helpful for carrier transport. Therefore, our result demonstrated the P-doping effect in the Si QD thin films by using a GSRO-ML structure.
Huang, Fang-Hsin, and 黃方信. "Development of a-Si TFT-LCD Utilizing Metal Oxide and Quantum Dot Materials." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/67837286571173868800.
Повний текст джерела元智大學
化學工程與材料科學學系
105
Amorphous silicon has been the main material for backplane technology for many years and has a variety of manufacturing methods,to improve its energy efficiency, refresh speeds, and the display’s viewing angle. Up to now, amorphous-Si (a-Si) displays still hold the smartphone display market approximately 37‒39 %. Although OLED growth is rapid, the next few years are double-digit growth, but TFT-LCD is still the mass stream. For mobile displays with a pixel density lower than 300 pixels per inch, this technology remains the preferable backplane of choice, mainly due to its low costs and relatively simple manufacturing process. However, when it comes to higher resolution displays and new technologies such as AMOLED, a-Si shows a significant display effect. Compared with a-Si TFT-LCD, AMOLED exerts more electrical stress on the transistors, thus facilitating the technique more current to each pixel. Furthermore, AMOLED pixel transistors take up more space, blocking the AMOLED display light emission, making a-Si rather unsuitable. And LTPS price is dropping, a-Si is losing its advantage. In 2015, LTPS already held 41% of the market, and it is believed that the percentage would exceed a-Si in 2017. As a result, new technologies and manufacturing processes have been developed to meet the increasing demands made of display panels over recent years. With industry trend and market demand for high definition and power-efficient display panels, metal oxides are rapidly becoming a suitable display technology. Indium gallium zinc oxide-thin-film transistor (IGZO-TFT) has the advantage of having power-efficient consumption than a-Si-TFT LCD panels. This technology is suitable for portable devices with high-resolution displays nonetheless. In LCD displays, Quantum dot (QD) technology is now offering a wide color gamut (WCG) that is consistently bigger than that offered by OLED displays and other LCD technologies. When coupled with high dynamic range (HDR), these displays offer the best picture performance on the market and are expected to be the main trend in the next wave of technology. This technical report will explore the metal oxide IGZO and quantum dot materials behind the technology, which can be used to manufacture LCD displays in various methods and spaces. The advantages and disadvantages of each method will be discussed in this report. Compared with the amorphous silicon, IGZO can reduce the size of the transistor about ½, so that the LCD panel pixel aperture rate increased, about twice the resolution. Its electron mobility is ten times faster while leakage current is much less than amorphous silicon, so the power consumption of mobile devices can be reduced to two-thirds. In term of performance, quantum dot with high-performance blue LED and traditional filters can be more than 50% of the traditional LCD performance, and the light efficiency and the color performance is also close to the OLED, but the process yield and material costs are far less than OLED. So the future display of quantum dot can be expected.
Tseng, Sheng-Hsiung, and 曾勝雄. "Germanium Quantum Dot Metal-Oxide-Semiconductor Photodiodes and Poly-Si Thin-Film Transistors." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/25413581707109533642.
Повний текст джерела國立中央大學
電機工程研究所
98
This thesis investigates the device physics and electrical characteristics of Ge-QD photodiodes (PDs) and hototransistors (PTs) fabricated in a complementary metal-oxide-semiconductor (CMOS) process. The main features encompass as follows. First, thermally oxidizing poly-Si0.87Ge0.13 onto a dielectric layer produces Ge QDs embedded in an SiO2 matrix to serve as an efficient absorption layer for visible to ultraviolet light. Secondly, we have successfully demonstrated the feasibility of MOS PDs including multi-layer Ge QDs in the gate oxide and elucidated the current–voltage characteristics in terms of zero, one and three Ge-QD layers. Ge-QD PDs exhibit dramatically enhanced current under light illumination in the inversion mode and amplified responsivity (quantum efficiency) from 4.64 (1.42%), through 482 (148%) to 812 (245%) mA/W, respectively, as the Ge-QD layer number increases from zero, through one to three. Shrinking Ge QD size from 9.1 nm to 5.1 nm reveals considerable blueshift in spectral peak energies, originating from the quantum confinement effect (QCE). The temperature and bias dependences on the dark current ascribe the charge transport mechanism to be percolation hopping. Thirdly, Ge-QD PTs are realized by double-gated thin-film transistors with Ge QDs in the top-gate dielectrics. Compared with the current in darkness, 405-450 nm light illumination strongly enhances drain current and improves the PTs’subthreshold characteristics, following from that only photo-excited holes within Ge QDs inject into the active channel via vertical electric field and contribute to photocurrent without the counterpart photo-generated electron-induced junction barrier lowering. Spectral responses of Ge-QD PTs are consistent with that of Ge-QD PDs, attributing the PTs’photo-absorption to QCE. Temperature-dependent and light pulse characterizations demonstrate Ge-QD PTs have great thermal stability and photo-absorption efficiency. These Ge-QD PDs and PTs offer a deterministic approach to integrate with Si-based electronics monolithically.
Shenoy, Bhamy Maithry. "Quantum-Continuum Modeling and Simulations of Semiconductor Nanostructures." Thesis, 2016. https://etd.iisc.ac.in/handle/2005/4380.
Повний текст джерелаHuang, Pin-Ruei, and 黃品睿. "High density Si quantum dot thin films using a gradient Si-rich oxide multilayer structure for photovoltaic devices application." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/rqe68w.
Повний текст джерела國立交通大學
顯示科技研究所
101
So far, the Si-based solar cell is the highest global market share and the good development potential due to the plentiful materials and the well-developed fabrication technique. In order to achieve the goal of the third generation solar cells with high efficiency and low cost, all Si-based multiple-junction solar cell is widely investigated and developed nowadays. The nano-crystalline Si quantum dot (QD) thin film is one of the potential structures to overcome the bandgap limitation of Si-based materials. Silicon-rich oxide (SRO) single layer and [SRO/SiO2] multilayer (ML) thin films are the most commonly used deposition structures for Si QD thin films. However, the former is hard to control the QD's size and density simultaneously, the latter exists the QD’s separation limitation due to the SiO2 barrier layers inserted. Furthermore, the QD’s density of both structures is still not high enough for a better PV application. These result in the difficulty for good photo-generated carrier’s transportation and high conversion efficiency. Hence, to efficiently improve the carrier’s transportation properties is a critical issue for the high efficiency Si-based solar cells integrating Si QD thin film. In this study, we propose a more potential deposition structure by a gradient Si-rich oxide multilayer (GSRO-ML) structure for the QD size control and the high QD density. The nano-structure, crystalline, and optical properties of Si QD thin films using a GSRO-ML structure had been studied. It also shows the better photovoltaic properties than that using a [SRO/SiO2]-ML structure. A higher conversion efficiency of Si QD thin films utilizing a GSRO-ML structure can be highly expected by using a heavy doping concentration in the near future.
Hsu, Shu-Wei, and 許書維. "Characteristics of the Nano-crystalline Si Quantum Dot Embedded ZnO Thin Films for Solar Cell Applications." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/15045537983700589933.
Повний текст джерела國立交通大學
光電工程學系
99
Researches of Si quantum dot (QD) thin film solar cell is fabricated by using nanocrystal silicon (nc-Si) QD embedded in the Si-based dielectric material. However the experimental results are still substantially lower than the theoretical value due to the unfavorable material characteristics of these Si-based matrices, that is, they are not electrically conductive. In this thesis, we propose to use Zinc oxide (ZnO) as the substitutable matrix material due to its many potential applications and unique features over other conventional wide band gap semiconductors such as high transparency, nice crystallinity, and easiness to control the electrical properties. Hence, ZnO is a suitable material to serve as the matrix for nano-crystalline Si thin film solar cells We deposited ZnO/Si multilayer thin films by radio-magnetron sputtering. At first part, the nc-Si QD formed after annealing by rapid thermal annealing thermal process. Then we investigated the nc-Si formation and crystalline quality of ZnO thin films by analyses of Raman spectra and XRD patterns. Optical-electrical properties of the multilayer thin films after annealing are also investigated. We observe that the sputtered Si atoms have more kinetic energy to aggregate together as Si nano-clusters under higher Si sputtering power. An obvious aggregation of the sputtered Si atoms during deposition is helpful for the formation of nc-Si and the better crystallization of the ZnO matrix in the nc-Si embedded ZnO thin films during the RTA process. At second part, we substitute RTA to furnace as our new thermal treatment equipment to solve some problems cause by RTA thermalprocess. Then, we observe good rectification ratio and better photon response after annealing by furnace. At the last part, we try to solve the film bending problem cause by the high stress interior the films after annealing. We observe film bending problem may be solved with a heated substrate during deposition.
Huang, Chun-Hsin, and 黃俊欣. "GaN on Si (111) Grown by Metalorganic Vapor phase Epitaxy (MOVPE) and Fabrication of Quantum Dot Photodetectors." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/31788935481694689353.
Повний текст джерела國立成功大學
電機工程學系專班
92
GaN films were grown on Si(111) substrates by home made MOVPE system using a vertical reactor. The low-temperature AlN buffer layer,30 nm in thickness, was grown on 7000C. The high temperature GaN films were grown at 10600C. XRD observation showed that the films are well oriented hexagonal GaN. But SEM observation showed that there were many cracks and defects in the films. The PL measurement results showed the light response of the films were not clear. We successfully fabricated a novel device: InGaN/GaN multi-quantum dot (MQD) p-n junction photodiodes, and discussed the characteristics of fabricated PDs. We achieved nanoscale InGaN self-assembled QDs in the well layers of the active region. It was found that the maximum responsivity of the fabricated MQD p-n junction PD was observed at 350 nm, and the responsivity was nearly a constant from 400 nm to 440 nm. It was also found that the minimum of spectral response was measured at 465 nm.
Abhale, Atul Prakash. "Laser Beam Induced Conductance Modulations as a Potential Microprobe in the Investigation of Defects and Inhomogeneities in Bulk Si and PbS, HgCdTe Quantum Dot Heterostructures." Thesis, 2017. http://etd.iisc.ac.in/handle/2005/3557.
Повний текст джерелаAbhale, Atul Prakash. "Laser Beam Induced Conductance Modulations as a Potential Microprobe in the Investigation of Defects and Inhomogeneities in Bulk Si and PbS, HgCdTe Quantum Dot Heterostructures." Thesis, 2017. http://etd.iisc.ernet.in/2005/3557.
Повний текст джерелаTsai, Yi-Wei, та 蔡一葦. "Studies of Strain Field of β - FeSi2 / Si Quantum Dot Nano-Structures by X-Ray Bragg-Surface Diffraction". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/23528057967960707147.
Повний текст джерелаWu, Wen-Wei, and 吳文偉. "Enhanced Growth of Low-Resistivity Metal Silicides and Self-Assembled Silicides Quantum Dot Arrays on Epitaxial Si-Ge Alloys on Silicon." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/64571933245719420108.
Повний текст джерела國立清華大學
材料科學工程學系
91
Enhanced growth of low-resistivity metal silicides and self-assembled NiSi and CoSi2 quantum dot arrays on epitaxial Si-Ge alloys have been studied by sheet resistance measurement, glancing incidence X-ray diffractometry (GIXRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), Auger electron spectroscopy (AES), secondary ion mass spectroscopy (SIMS), and energy dispersion analysis of X-ray (EDAX). The formation of Co silicides on (001) Si with an interposing Ni layer has been investigated. For Co(20 nm)/Ni(7 nm)/Si(001) samples, CoSi2 and NiSi phase were observed to form at 400-500 ºC. AES analysis indicated that Ni diffused from the Co/Si interface to disperse in CoSi2 layer during annealing. Above 700 ºC, (Co,Ni)Si2 was the only silicide phase present. The presence of Ni was found to decrease the formation temperature of CoSi2 by about 100 ºC, prevent oxygen contamination from the annealing ambient, and improve uniformity of CoSi2 compared to that without Ni interlayer. In addition, the resulting (Co,Ni)Si2 layer has good thermal stability up to 1000 ºC and has a preferential epitaxial orientation with respect to the Si substrate. Formation of Co silicides on Si0.7Ge0.3 alloys with a thin interposing Au layer and capping Ti layer has been investigated. CoSi2 was observed to be the only silicide phase in Si0.7Ge0.3 samples annealed at 650-950 ℃ with a thin interposing Au layer and capping Ti layer. The sequence of phase formation is the same as the reaction of Co with (001)Si. The presence of Au was found to decrease the formation temperature of CoSi2 by about 300 ℃ compared to that of Co(30nm)/Si0.7Ge0.3 samples. In addition, a thin capping Ti layer improves the uniformity and thermal stability of CoSi2 layer. For Ti(5nm)/Co(30nm)/Au(1nm)/Si0.7Ge0.3 system, the process window of CoSi2 was extended to 650-950 ℃. SIMS analysis indicated that a large amount of Au diffused from the Co/Si0.7Ge0.3 interface to disperse in the CoSi2 layer during annealing. Enhanced growth of low-resistivity self-aligned CoSi2, C54-TiSi2, and NiSi on epitaxial Si0.7Ge0.3 has been achieved with an interposing amorphous Si (a-Si) layer. The a-Si layer was used as a sacrificial layer with appropriate thickness to prevent Ge segregation, decrease the growth temperature, as well as maintain the interface flatness and morphological stability in forming CoSi2, C54-TiSi2, and NiSi on Si0.7Ge0.3 grown by molecular beam eptiaxy. The process promises to be applicable to the fabrication of high-speed Si-Ge devices. Self-assembled NiSi and CoSi2 quantum dot arrays have been grown on relaxed epitaxial Si0.7Ge0.3 on (001)Si. The formation of the one-dimensional ordered structure is attributed to the nucleation of NiSi nanodots on the surface undulations induced by step bunching on the surface of SiGe film owing to the miscut of the wafers from normal to the (001)Si direction. The two-dimensional, pseudo-hexagonal structure was achieved under the influence of repulsive stress between nanodots. Since the periodicity of surface bunching can be tuned with appropriate vicinality and misfit, the undulated templates promise to facilitate the growth of ordered silicide quantum dots with selected periodicity and size for utilization in nanodevices.
"Photoluminescence Enhancement of Ge Quantum Dots by Exploiting the Localized Surface Plasmon of Epitaxial Ag Islands." Doctoral diss., 2015. http://hdl.handle.net/2286/R.I.34762.
Повний текст джерелаDissertation/Thesis
Doctoral Dissertation Physics 2015
Cho, Benjamin. "P incorporation during Si(001) : P gas-source molecular beam epitaxy : effects on film growth kinetics, surface morphology, and the self-organization of germanium quantum dot overlays /." 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3269859.
Повний текст джерелаSource: Dissertation Abstracts International, Volume: 68-07, Section: B, page: 4759. Adviser: Joseph E. Greene. Includes bibliographical references. Available on microfilm from Pro Quest Information and Learning.
Tauchnitz, Tina. "Novel Methods for Controlled Self-Catalyzed Growth of GaAs Nanowires and GaAs/AlxGa1-xAs Axial Nanowire Heterostructures on Si Substrates by Molecular Beam Epitaxy." 2019. https://tud.qucosa.de/id/qucosa%3A38708.
Повний текст джерелаGaAs-basierte Nanodrähte sind attraktive Bausteine für die Entwicklung von zukünftigen (opto)elektronischen Bauelementen dank ihrer exzellenten intrinsischen Materialeigenschaften wie zum Beispiel die direkte Bandlücke und die hohe Elektronenbeweglichkeit. Eine Voraussetzung für die Realisierung neuer Funktionalitäten auf einem einzelnen Si Chip ist die monolithische Integration der Nanodrähte auf der etablierten Si-Metall-Oxid-Halbleiter-Plattform (CMOS) mit präziser Kontrolle des Wachstumsprozesses der Nanodrähte. Das selbstkatalytische (Ga-unterstützte) Wachstum von GaAs Nanodrähten auf Si(111)-Substrat mittels Molekularstrahlepitaxie bietet die Möglichkeit vertikale Nanodrähte mit vorwiegend Zinkblende-Struktur herzustellen, während die potentielle Verunreinigung der Nanodrähte und des Substrats durch externe Katalysatoren wie Au vermieden wird. Obwohl der Wachstumsmechanismus gut verstanden ist, erweist sich die Kontrolle der Nukleationsphase, Anzahldichte und Kristallstruktur der Nanodrähte als sehr schwierig. Darüber hinaus sind relativ hohe Temperaturen im Bereich von 560-630 °C in konventionellen Wachstumsprozessen notwendig, die deren Anwendung auf der industriellen Si Plattform begrenzen. Die vorliegende Arbeit liefert zwei originelle Methoden um die bestehenden Herausforderungen in konventionellen Wachstumsprozessen zu bewältigen. Im ersten Teil dieser Arbeit wurde eine einfache Prozedur, bezeichnet als surface modification procedure (SMP), für die in situ Vorbehandlung von nativem-SiOx/Si(111)-Substrat entwickelt. Die Substratvorbehandlung mit Ga-Tröpfchen und zwei Hochtemperaturschritten vor dem Wachstumsprozess ermöglicht eine synchronisierte Nukleation aller Nanodrähte auf ihrem Substrat und folglich das Wachstum von sehr gleichförmigen GaAs Nanodraht-Ensembles mit einer sub-Poisson Verteilung der Nanodrahtlängen. Des Weiteren kann die Anzahldichte der Nanodrähte unabhängig von deren Abmessungen und ohne ex situ Vorstrukturierung des Substrats über drei Größenordnungen eingestellt werden. Diese Arbeit liefert außerdem ein grundlegendes Verständnis zur Nukleationskinetik von Ga-Tröpfchen auf nativem-SiOx und deren Wechselwirkung mit SiOx und bestätigt theoretische Voraussagen zum sogenannten Nukleations-Antibunching, dem Auftreten einer zeitlichen Anti-Korrelation aufeinanderfolgender Nukleationsereignisse. Im zweiten Teil dieser Arbeit wurde eine alternative Methode, bezeichnet als droplet-confined alternate-pulsed epitaxy (DCAPE), für das selbstkatalytische Wachstum von GaAs Nanodrähten und GaAs/AlxGa1-xAs axialen Nanodraht-Heterostrukturen entwickelt. DCAPE ermöglicht das Nanodrahtwachstum bei unkonventionell geringeren Temperaturen im Bereich von 450-550 °C und ist vollständig kompatibel mit der Standard-Si-CMOS-Plattform. Der neue Wachstumsansatz erlaubt eine präzise Kontrolle der Kristallstruktur der Nanodrähte und folglich das Wachstum von defektfreien Nanodrähten mit phasenreiner Zinkblende-Struktur. Die Stärke der DCAPE Methode wird des Weiteren durch das kontrollierte Wachstum von GaAs/AlxGa1-xAs axialen Quantentopf-Nanodrähten mit abrupten Grenzflächen und einstellbarer Dicke und Al-Anteil der AlxGa1-xAs-Segmente aufgezeigt. Die GaAs/AlxGa1-xAs axialen Nanodraht-Heterostrukturen sind interessant für den Einsatz als Einzelphotonen-Emitter mit einstellbarer Emissionswellenlänge, wenn diese mit gitterfehlangepassten InxAl1-xAs-Schichten in einer Kern-Hülle-Konfiguration überwachsen werden. Alle Ergebnisse dieser Arbeit tragen dazu bei, den Weg für eine erfolgreiche monolithische Integration von sehr gleichförmigen GaAs-basierten Nanodrähten mit kontrollierbarer Anzahldichte, Abmessungen und Kristallstruktur auf der industriell etablierten Si-Plattform zu ebnen.