Properties of amorphous silicon-germanium films and devices deposited at higher growth rates

2002 ◽  
Vol 715 ◽  
Author(s):  
Yong Liu ◽  
Vikram L. Dalal
Keyword(s):  
Amorphous Silicon ◽  
Growth Rates ◽  
Silicon Germanium ◽  
Urbach Energy ◽  
Dark Conductivity ◽  
Film Properties ◽  
Ecr Plasma ◽  
Device Properties ◽  
Amorphous Silicon Germanium ◽  
Defect Densities

AbstractWe report on the growth and properties of amorphous Silicon-Germanium [a–(Si,Ge):H] films and devices fabricated at growth rates of ∼ 5 Å/sec using a remote ECR plasma growth process. The films and devices were made using mixtures of germane and silane along with dilution with hydrogen and helium. The addition of He to the gas mixture significantly increased the growth rates. It was found that hydrogen was always necessary in order to achieve the best film and device properties. Films and devices were made across the entire bandgap range, from a-Si to a-Ge. High ratios of photo/dark conductivity and low values of Urbach energy ( > 50 meV) indicate good film properties. The defect densities were measured using space charge limited current techniques. The defect densities were in the range of 1-2 x 10 16/cm 3 –eV, about 5 times higher than for a-Si:H. Electron mobility-lifetime products were measured and found to be in the range of 2-4 x 10-7 cm2/V, even for low gap materials (1.35 eV). Single and graded gap devices were fabricated in these materials. Device fill factors of ∼ 70% were obtained in graded gap devices.

Effect of Ge Incorporation on Hydrogenated Amorphous Silicon Germanium Thin Films Prepared by Plasma Enhanced Chemical Vapor Deposition

2012 ◽  
Vol 569 ◽  
pp. 27-30
Author(s):  
Bao Jun Yan ◽  
Lei Zhao ◽  
Ben Ding Zhao ◽  
Jing Wei Chen ◽  
Hong Wei Diao ◽  
...  
Keyword(s):  
Thin Films ◽  
Chemical Vapor Deposition ◽  
Amorphous Silicon ◽  
Vapor Deposition ◽  
Silicon Germanium ◽  
Hydrogenated Amorphous Silicon ◽  
Chemical Vapor ◽  
Dark Conductivity ◽  
Amorphous Silicon Germanium ◽  
Hydrogenated Amorphous

Hydrogenated amorphous silicon germanium thin films (a-SiGe:H) were prepared via plasma enhanced chemical vapor deposition (PECVD). By adjusting the flow rate of GeH4, a-SiGe:H thin films with narrow bandgap (Eg) were fabricated with high Ge incorporation. It was found that although narrow Eg was obtained, high Ge incorporation resulted in a great reduction of the thin film photosensitivity. This degradation was attributed to the increase of polysilane-(SiH2)n, which indicated a loose and disordered microstructure, in the films by systematically investigating the optical, optoelectronic and microstructure properties of the prepared a-SiGe:H thin films via transmission, photo/dark conductivity, Raman spectroscopy, and Fourier transform infrared spectroscopy (FTIR) measurements. Such investigation provided a helpful guide for further preparing narrow Eg a-SiGe:H materials with good optoelectronic properties.

Light-Induced Degradation of Amorphous Silicon-Germanium Alloy Solar Cells Deposited at High Rates

1996 ◽  
Vol 420 ◽  
Author(s):  
S. Sugiyama ◽  
X. Xu ◽  
J. Yang ◽  
S. Guha
Keyword(s):  
Solar Cells ◽  
Glow Discharge ◽  
Amorphous Silicon ◽  
Silicon Germanium ◽  
Ion Bombardment ◽  
Ir Absorption ◽  
Film Properties ◽  
Deposition Rates ◽  
Rf Glow Discharge ◽  
Amorphous Silicon Germanium

AbstractWe have studied the light-induced degradation of amorphous silicon-germanium (a-SiGe:H) alloy single-junction solar cells with high initial performance deposited at high rates. The intrinsic layers were deposited using microwave (MW) glow-discharge technique at deposition rates between 10 and 40 Å/s. The results show that light-induced degradation of the cells is higher than that of cells deposited at low rates using RF glow-discharge technique, and it does not strongly depend on deposition rates over this range. The total hydrogen content and the ratio of Si-H2, Ge-H, and Ge-H2 to Si-H bonding estimated by infrared (IR) absorption in films are correlated with the cell degradation results. We have also investigated the effect of ionbombardment on film properties. Films with low ion-bombardment are more porous and have higher composition of Si-H2 and Ge-H2 bonding. Appropriate ion-bombardment makes denser structure in a-SiGe:H alloy films deposited at high rates. This improves the cell performance as well.

Effects of high hydrogen dilution at low temperature on the film properties of hydrogenated amorphous silicon germanium

1997 ◽  
Vol 71 (1) ◽  
pp. 84-86 ◽  
Author(s):  
Masaki Shima ◽  
Akira Terakawa ◽  
Masao Isomura ◽  
Makoto Tanaka ◽  
Seiichi Kiyama ◽  
...  
Keyword(s):  
Low Temperature ◽  
Amorphous Silicon ◽  
Silicon Germanium ◽  
Hydrogenated Amorphous Silicon ◽  
Film Properties ◽  
High Hydrogen ◽  
Hydrogen Dilution ◽  
Amorphous Silicon Germanium ◽  
Hydrogenated Amorphous

Metastable Defects in the Amorphous Silicon-Germanium Alloys

2003 ◽  
Vol 762 ◽  
Author(s):  
J. David Cohen
Keyword(s):  
Amorphous Silicon ◽  
Silicon Germanium ◽  
Dangling Bonds ◽  
Annealing Behavior ◽  
Fundamental Properties ◽  
Silicon Materials ◽  
Salient Features ◽  
The Individual ◽  
Amorphous Silicon Germanium ◽  
Silicon Germanium Alloys

AbstractThis paper first briefly reviews a few of the early studies that established some of the salient features of light-induced degradation in a-Si,Ge:H. In particular, I discuss the fact that both Si and Ge metastable dangling bonds are involved. I then review some of the recent studies carried out by members of my laboratory concerning the details of degradation in the low Ge fraction alloys utilizing the modulated photocurrent method to monitor the individual changes in the Si and Ge deep defects. By relating the metastable creation and annealing behavior of these two types of defects, new insights into the fundamental properties of metastable defects have been obtained for amorphous silicon materials in general. I will conclude with a brief discussion of the microscopic mechanisms that may be responsible.

Properties of Catalytic-Cvd Amorphous Silicon-Germanium (a-SiGe:H)

1990 ◽  
Vol 192 ◽  
Author(s):  
Hideki Matsumura ◽  
Masaaki Yamaguchi ◽  
Kazuo Morigaki
Keyword(s):  
Amorphous Silicon ◽  
Silicon Germanium ◽  
Hydrogenated Amorphous Silicon ◽  
Chemical Vapor ◽  
Characteristic Energy ◽  
Optical Band Gaps ◽  
Spin Resonance ◽  
Amorphous Silicon Germanium ◽  
Conductive Properties ◽  
Hydrogenated Amorphous

ABSTRACTHydrogenated amorphous silicon-germanium (a-SiGe:H) films are prepared by the catalytic chemical vapor deposition (Cat-CVD) method using a SiH4, GeH4 and H4 gas mixture. Properties of the films are investigated by the photo-thermal deflection spectroscopy (PDS) and electron spin resonance (ESR) measurements, in addition to the photo-conductive and structural studies. It is found that the characteristic energy of Urbach tail, ESR spin density and other photo-conductive properties of Cat-CVD a-SiGe:H films with optical band gaps around 1.45 eV are almost equivalent to those of the device quality glow discharge hydrogenated amorphous silicon (a-Si:H).

Medium-Range Order of Amorphous Silicon Germanium Alloys: Small-Angle X-Ray Scattering Study

1989 ◽  
Vol 28 (Part 2, No. 7) ◽  
pp. L1092-L1095 ◽  
Author(s):  
Shin-ichi Muramatsu ◽  
Toshikazu Shimada ◽  
Hiroshi Kajiyama ◽  
Kazufumi Azuma ◽  
Takeshi Watanabe ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Small Angle ◽  
Silicon Germanium ◽  
Range Order ◽  
Medium Range Order ◽  
X Ray ◽  
X Ray Scattering ◽  
Medium Range ◽  
Scattering Study ◽  
Amorphous Silicon Germanium

Amorphous silicon-germanium alloy multilayers for solar cells

1988 ◽  
Author(s):  
J.P. Conde ◽  
V. Chu ◽  
S. Tanaka ◽  
D.S. Shen ◽  
S. Wagner
Keyword(s):  
Solar Cells ◽  
Amorphous Silicon ◽  
Silicon Germanium ◽  
Germanium Alloy ◽  
Amorphous Silicon Germanium
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