SiGe Thin-Film Structures for Solar Cells

1997 ◽  
Vol 485 ◽  
Author(s):  
G. Bremond ◽  
A. Daami ◽  
A. Laugier ◽  
W. Seifert ◽  
M. Kittler ◽  
...  
Keyword(s):  
Solar Cells ◽  
Buffer Layer ◽  
Base Material ◽  
Chemical Vapor ◽  
Base Layer ◽  
Electrical Measurements ◽  
Remote Plasma ◽  
Si Substrates ◽  
Plasma Hydrogenation ◽  
Active Base

AbstractIn order to study their applicability as the active base material in Si thin crystalline film solar cell technology, SiGe relaxed layers grown by Liquid Phase Epitaxy (LPE) and Chemical Vapor Deposition (CVD) on Si substrates are investigated by optical and electrical measurements (TEM, EXD, PL, EBIC). The main results of this work is to point out the improvement of the SiGe active base layer by using smooth Ge graded SiGe buffer layer and remote plasma hydrogenation. TEM, EXD, PL experiments show the effect of the Ge graded buffer layer grown using LPE, by confining the threading dislocations in the SiGe buffer layer close to the Si/SiGe interface. EBIC measurements reveal low recombination activity of dislocations at 300 K providing the diffusion length exceeds the 15 μm layer thickness The enhanced luminescence of SiGe near bandgap indicates that remote plasma hydrogenation induces a decrease of the non-radiative recombination pathways due to dislocations on CVD layers where defect recombinations dominate as indicated by EBIC measurements.This study points out the importance of controlling relaxed SiGe layers with good minority carrier recombination quality as a key issue for the optimization of new SiGe/Si based solar cells.

Microcrystalline (Si,Ge):H Solar Cells

2003 ◽  
Vol 762 ◽  
Author(s):  
Jianhua Zhu ◽  
Vikram L. Dalal
Keyword(s):  
Solar Cells ◽  
Buffer Layer ◽  
Quantum Efficiency ◽  
Fill Factor ◽  
Open Circuit Voltage ◽  
Defect Density ◽  
Cell Structure ◽  
Open Circuit ◽  
Base Layer ◽  
Ecr Plasma

AbstractWe report on the growth and properties of microcrystalline Si:H and (Si,Ge):H solar cells on stainless steel substrates. The solar cells were grown using a remote, low pressure ECR plasma system. In order to crystallize (Si,Ge), much higher hydrogen dilution (∼40:1) had to be used compared to the case for mc-Si:H, where a dilution of 10:1 was adequate for crystallization. The solar cell structure was of the p+nn+ type, with light entering the p+ layer. It was found that it was advantageous to use a thin a-Si:H buffer layer at the back of the cells in order to reduce shunt density and improve the performance of the cells. A graded gap buffer layer was used at the p+n interface so as to improve the open-circuit voltage and fill factor. The open circuit voltage and fill factor decreased as the Ge content increased. Quantum efficiency measurements indicated that the device was indeed microcrystalline and followed the absorption characteristics of crystalline ( Si,Ge). As the Ge content increased, quantum efficiency in the infrared increased. X-ray measurements of films indicated grain sizes of ∼ 10nm. EDAX measurements were used to measure the Ge content in the films and devices. Capacitance measurements at low frequencies ( ~100 Hz and 1 kHz) indicated that the base layer was indeed behaving as a crystalline material, with classical C(V) curves. The defect density varied between 1x1016 to 2x1017/cm3, with higher defects indicated as the Ge concentration increased.

Heteroepitaxial Growth of 3C-SiC on Si (111) Substrate Using AlN as a Buffer Layer

2008 ◽  
Vol 600-603 ◽  
pp. 251-254 ◽  
Author(s):  
Yong Mei Zhao ◽  
Guo Sheng Sun ◽  
Xing Fang Liu ◽  
Jia Ye Li ◽  
Wan Shun Zhao ◽  
...  
Keyword(s):  
Buffer Layer ◽  
Chemical Vapor ◽  
Heteroepitaxial Growth ◽  
Si Substrate ◽  
Si Substrates ◽  
Good Crystallinity ◽  
Aln Film ◽  
Pressure Chemical ◽  
Aln Buffer ◽  
Sic Film

Using AlN as a buffer layer, 3C-SiC film has been grown on Si substrate by low pressure chemical vapor deposition (LPCVD). Firstly growth of AlN thin films on Si substrates under varied V/III ratios at 1100oC was investigated and the (002) preferred orientational growth with good crystallinity was obtained at the V/III ratio of 10000. Annealing at 1300oC indicated the surface morphology and crystallinity stability of AlN film. Secondly the 3C-SiC film was grown on Si substrate with AlN buffer layer. Compared to that without AlN buffer layer, the crystal quality of the 3C-SiC film was improved on the AlN/Si substrate, characterized by X-ray diffraction (XRD) and Raman measurements.

Advanced Deposition Phase Diagrams for Guiding Si:H-Based Multijunction Solar Cells

2007 ◽  
Vol 989 ◽  
Author(s):  
Jason Collins ◽  
Nikolas J. Podraza ◽  
Jian Li ◽  
Xinmin Cao ◽  
Xunming Deng ◽  
...  
Keyword(s):  
Solar Cells ◽  
Phase Diagrams ◽  
Silicon Germanium ◽  
Chemical Vapor ◽  
Very High Frequency ◽  
Hydrogenated Silicon ◽  
Si Substrates ◽  
Cell Structures ◽  
Multijunction Solar Cells ◽  
Back Reflectors

AbstractPhase diagrams have been established to describe very high frequency (vhf) plasma-enhanced chemical vapor deposition (PECVD) processes for intrinsic hydrogenated silicon (Si:H) and silicon-germanium alloy (Si1-xGex:H) thin films using crystalline Si substrates that have been over-deposited with n-type amorphous Si:H (a-Si:H). The Si:H and Si1-xGex:H processes are applied for the top and middle i-layers of triple-junction a-Si:H-based n-i-p solar cells fabricated at University of Toledo. Identical n/i cell structures were co-deposited on textured Ag/ZnO back-reflectors in order to correlate the phase diagram and the performance of single-junction solar cells, the latter completed through over-deposition of the p-layer and top contact. This study has reaffirmed that the highest efficiencies for a-Si:H and a-Si1-xGex:H solar cells are obtained when the i-layers are prepared under maximal H2 dilution conditions.

Formation of an Interfacial Buffer Layer for 3C-SiC Heteroepitaxy on AlN/Si Substrates

2014 ◽  
Vol 778-780 ◽  
pp. 251-254 ◽  
Author(s):  
Kazuki Meguro ◽  
Tsugutada Narita ◽  
Kaon Noto ◽  
Hideki Nakazawa
Keyword(s):  
Chemical Vapor Deposition ◽  
Low Temperature ◽  
Surface Morphology ◽  
Buffer Layer ◽  
Vapor Deposition ◽  
Intermediate Layer ◽  
Chemical Vapor ◽  
Si Substrates ◽  
Pressure Chemical ◽  
Sic Films

We have formed a SiC interfacial buffer layer on AlN/Si substrates at a low temperature by low-pressure chemical vapor deposition (LPCVD) using monomethylsilane (CH3SiH3; MMS), and grew 3C-SiC films on the low-temperature buffer layer by LPCVD using MMS. We investigated the surface morphology and crystallinity of the grown SiC films. It was found that the formation of the SiC buffer layer suppressed the outdiffusion of Al and N atoms from the AlN intermediate layer to the SiC films and further improved the surface morphology and crystallinity of the films.

A Study on Impact of Process Parameters to Metal Organic Chemical Vapor Deposition Grown (002) Zinc Oxide Thin Films, at 320°C

2002 ◽  
Vol 744 ◽  
Author(s):  
Yuneng Chang ◽  
Hengchuan Lu ◽  
Yumeng Hung ◽  
Chunsung Lee ◽  
Jianming Chen ◽  
...  
Keyword(s):  
Growth Rate ◽  
Water Vapor ◽  
Buffer Layer ◽  
Chemical Vapor ◽  
Organic Chemical ◽  
Zno Films ◽  
Key Factors ◽  
Si Substrates ◽  
Metal Organic ◽  
Zno Buffer Layer

ABSTRACTThis paper reports preparation of highly oriented (002) ZnO films by atmospheric pressure CVD at 320°C, which is far below previous reported values. In this study, a cold wall horizontal system was used to thermally decompose sublimed zinc acetylacetonate (Zn(acac)2, Zn(C5H702)2) vapor, and reacted with water vapor to produce ZnO films at temperatures above 320°C. Through experimental data, we discovered that low deposition temperature, using water vapor as co-reactant and substrates with ZnO buffer layer pre-coated by PVD are the key factors to prepare (002) ZnO films. By using Si(100) pre-coated with sputtered ZnO amorphous buffer layer as substrates, the ZnO growth rate is highest. While using copper oxide pre-coated Si substrates gave the lowest growth rate, and deposited ZnO film is amorphous. Considering influence of CVD co-reactant, using Zn(acac)2 and water vapor gives higher growth rate and better crystallinity than CVD using Zn(acac)2 and oxygen. Water vapor may supply hydrogen to react with released acetylacetonyl ligand (C5H7O2), and help the formation of stable acetylaceton (C5H8O2) molecule. DPA shows that film contain 46% O and 54% Zn. XPS of Zn Auger identified the valence of Zn being Zn2+. It seems that excessive Zn might present as discrete Zn2+ dispersed between ZnO lattices.

Sub-Nanometer-Equivalent PZT Thin Films Fabricated by Low-Temperature MOCVD

1992 ◽  
Vol 284 ◽  
Author(s):  
Hiroshi Miki ◽  
Yuzuru Ohji ◽  
Shinichi Tachi
Keyword(s):  
Vapor Deposition ◽  
Chemical Vapor ◽  
Organic Chemical ◽  
Electrical Measurements ◽  
Reduced Pressure ◽  
Pzt Thin Films ◽  
Si Substrates ◽  
Pzt Films ◽  
Metal Organic ◽  
Organic Chemical Vapor Deposition

ABSTRACTFerroelectric PZT (Pb (Zr,Ti)O3) from 100 nm down to 50 nm thick was deposited on Pt/SiO2/Si substrates using MOCVD (Metal Organic Chemical Vapor Deposition) under reduced pressure at 550°C. Using Pb (DPM)2, Zr (DPM)4, and Ti(i–OC3H7)4 as precursors made it possible to control the composition of CVD films and to produce pure perovskite crystalline structure in the range of thickness less than 100 nm. Electrical measurements of the capacitors revealed that 50-nm PZT films typically had a dielectric constant of 500, resulting in the same capacitance as 0.4-nm SiO2.

InGaAs Solar Cells Grown on Wafer-Bonded InP/Si Epitaxial Templates

2007 ◽  
Vol 1012 ◽  
Author(s):  
James M. Zahler ◽  
Katsuaki Tanabe ◽  
Corinne Ladous ◽  
Tom Pinnington ◽  
Frederick D. Newman ◽  
...  
Keyword(s):  
Solar Cells ◽  
Chemical Vapor ◽  
Organic Chemical ◽  
Si Substrates ◽  
Current Voltage ◽  
Metal Organic ◽  
Engineered Substrates ◽  
The Cost ◽  
Inp Substrates ◽  
Organic Chemical Vapor Deposition

AbstractInP/Si engineered substrates formed by wafer bonding and layer transfer have the potential to significantly reduce the cost and weight of III-V compound semiconductor solar cells. InP/Si substrates were prepared by He implantation of InP prior to bonding to a thermally oxidized Si substrate and annealing to exfoliate an InP thin film. Following thinning to remove damage caused by the implantation and exfoliation from the surface of the InP transferred film, InGaAs solar cells lattice-matched to bulk InP were grown on those substrates using metal-organic chemical vapor deposition. The photovoltaic current-voltage characteristics of the InGaAs cells fabricated on the wafer-bonded InP/Si substrates were comparable to those synthesized on commercially available epi-ready InP substrates, thus providing an initial demonstration of wafer-bonded InP/Si substrates as an alternative to bulk InP substrates for solar cell applications.

Porous Silicon: A Possible Buffer Layer for Diamond Growth on Silicon Substrates

1994 ◽  
Vol 358 ◽  
Author(s):  
Zhaohui Liu ◽  
B.Q. Zong ◽  
Zhangda Lin
Keyword(s):  
Porous Silicon ◽  
Buffer Layer ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Nucleation And Growth ◽  
Diamond Growth ◽  
Silicon Substrates ◽  
Nanoscale Structures ◽  
Si Substrates ◽  
Hot Filament

ABSTRACTContinuous diamond films have been grown on porous silicon by hot filament chemical vapor deposition. The demonstration of diamond growth on porous silicon seems to suggest that porous silicon can act as a buffer layer for diamond growth on Si substrates, and that the nanoscale structures of porous silicon play an important role in nucleation and growth of diamond.

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