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In this investigation, SiGe compounds allowed a variation of the extent and size of the initial elastic stress, to determine correlations between growth conditions and crystalline perfection of the heterostructures (HS). Some structures were grown by Molecular Beam Epitaxy (MBE) on Si(001) substrates at 605??C, and others on Ge(001) substrates at 440??C, with the growth rate ranging from 1.35 to 2...
In this paper, the graphene nanoelectronics progress in synthesizing wafer-scale monolayer-controlled graphene and fabricating high-speed graphene FETs (GFET) with the highest value reported cut-off frequency (f??) approaching 100 GHz was reported. Epitaxial growth was investigated to produce wafer-scale, high-quality graphene on SiC substrate. Low-energy electron diffraction microscopy, electron...
We have fabricated and characterized the field effect transistors having epitaxial-graphene channel grown on Si substrates. Epitaxial graphene is usually formed on SiC substrates by ultrahigh-vacuum (UHV) annealing. We used an approach to grow 3C-SiC(111) on Si substrates and subsequently to anneal it in UHV to make few layers of graphene on the sample surface. Backgate transistors using the SiC layer...
In this study, we report a direct comparison between two epitaxial silicon processes: 500degC using SiH4 and 350degC using Si3H8. Following four different metrics, we demonstrate that the reduction of silicon growth temperature results into the introduction of negatively charged defects possibly located at the Si/SiO2interface. However, the Epi Si growth at 350degC with Si3H8 remains beneficial compared...
With device scaling, the introduction of emerging materials including nanowires and nanodots is required more than ever. We present several examples of making nanomaterials based on advanced thin film deposition techniques including atomic layer deposition, supercritical fluid deposition (SCFD), and selective epitaxial growth (SEG), and nanohybrid process utilizing self-assembled nano-template. Metallic...
The aim of this paper is to present in-situ and cost-effective processes for crystalline silicon thin-film solar cells grown by high-temperature chemical vapour deposition on low-cost silicon substrates. The central approach is the epitaxial wafer-equivalent (EpiWE) cell structure, consisting of an epitaxial layer deposited on a low-cost silicon substrate. This EpiWE is then processed using a standard...
We report the fabrication of film c-Si solar cells on Si wafer templates by hot wire chemical vapor deposition. These devices, grown at glass-compatible temperatures below 750?? C, demonstrate open-circuit voltages greater than 500 mV and efficiencies above 5%. Analysis of the device characteristics and quantum efficiency provides important information about the epitaxial c-Si absorber material quality...
N-type thin-film polycrystalline-silicon solar cells were fabricated on alumina substrates. The polycrystalline silicon material was made by overdoping of AIC seed layers with phosphorus atoms followed by epitaxial thickening with low-pressure chemical vapor deposition (LPCVD) at 1000??C. The cells have i/p+ amorphous Si heterojunction emitters and show an average VOC of 455 mV, an average JSC of...
Single crystalline-like Ge films have been successfully grown on flexible polycrystalline substrates using templates created by ion beam assisted deposition (IBAD). No epitaxial growth was found to be possible when Ge is directly grown on MgO. However an intermediate layer of CeO2 was found to enable epitaxial growth of Ge. Also, textured Si has been demonstrated on CeO2-buffered IBAD templates on...
Epitaxial thin film silicon solar cell technology, consisting of a thin high quality epitaxial layer on top of a highly doped low-cost silicon substrate, is one of the most promising midterm alternatives for cost effective industrial solar cell manufacturing. Currently, CVD is used to grow the active layer. However, besides the growth of the base, also the emitter can be grown by CVD, which allows...
Thin Si solar cell with epitaxial lateral overgrowth (ELO) structure described in this paper should demonstrate higher voltage. PC-1D program has been used to study the open circuit voltage and efficiency as a function of the thin Si thickness and light trapping. According to the simulation results, high voltage can be obtained even without light trapping on the backside of the thin Si layer. Thin...
Epitaxial crystal silicon films 2 to 10-microns thick on high-quality seed layers have the potential to approach wafer silicon photovoltaic efficiencies at thin-film area costs. Using hot-wire chemical vapor deposition (HWCVD) from silane precursor gas, we have grown epitaxial layers up to 40-microns thick with defect densities of about 2 ?? 105 cm-2, corresponding to defects separated by more than...
Heteroepitaxy SiGe on Si by liquid phase epitaxy (LPE) is a potential material for photovoltaic application. The Si0.05Ge0.95 solar cell with an energy gap of 0.72 eV can lead to a 7 percentage point increase in the Si-based multi-bandgap system or any multi-bandgap system that contains Si as the 1.1 eV solar cell. In this initial work we report first growth SixGe1-x with 0.5<x<1 on Si substrate...
High efficiency multijunction solar cells are usually grown on expensive III-V or germanium semiconductor substrates. Growing thin layers of III-V semiconductors on a low cost silicon substrate can reduce the cost. The low lattice constant mismatch between gallium phosphide (GaP) and Si (0.37%) is favorable for epitaxial growth. In this paper, we will demonstrate that gallium phosphide has been epitaxially...
A scalable, self-aligned In0.53Ga0.47As MOSFET process was developed and enhancement mode device operation was demonstrated. The 0.7 mum Lg device shows a maximum drive current of 0.14 mA/mum at Vgs=4.0 V and Vds=2.5 V. The devices have almost an order of magnitude larger drive current than our previously reported MOSFETs. The channel layer was 5 nm thick InGaAs with InAlAs bottom barrier for vertical...
We have improved in-plane uniformity of crystal shape for InGaAs micro-discs using a multi-step growth in micro-channel selective-area metal-organic vapor phase epitaxy on Si(111) substrates. The multi-step growth employs a gas flow sequence in which the partial pressure of a Ga source is modulated to control the initial nucleation and the growth mode. At the initial stage of growth, we grew InAs...
InP on Si is grown by nano-epitaxial lateral overgrowth (nano-ELOG) on patterns consisting of net-type openings under different growth conditions. Analysis shows that net-type patterns yield large lateral growth rate and good optical quality. Different growth conditions have a substantial impact on growth rate and some effect on surface morphology, as well as on the optical quality. Optical quality...
A simple analytical model for segregation and redistribution of ion implanted erbium during solid phase epitaxial recrystallization in silicon has been developed. During the recrystallization process, defects at the crystalline-amorphous interface act as dynamic traps for erbium. When density of erbium in the segregation spike at the growth front exceeds the interface trap density, the excess erbium...
We demonstrate selectively grown Ge/Si avalanche photodetectors with a bandwidth of 10 GHz at gain = 8 at 1310 nm. The high bandwidth-gain-product of 80 GHz and Si monolithic integration capability offer great potentials for future applications.
Epitaxial growth of silicon on heavily boron-doped Si(111) surface was investigated. In our experiments, we found a new growth mode in the very initial stage for boron-coverage below 0.5 monolayer (ML) likely associated with defect-induced nucleation of Si islands. The initially stage of growth on boron-covered Si(111) could be interpreted by a quasi van der Waals like epitaxy, where Si adatoms catch...
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