Hydrogenated amorphous silicon germanium alloy with enhanced photosensitivity prepared by plasma enhanced chemical vapor deposition at high temperature

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.

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Optimization of hydrogenated amorphous silicon germanium thin films and solar cells deposited by hot wire chemical vapor deposition

Thin Solid Films ◽

10.1016/j.tsf.2015.05.055 ◽

2015 ◽

Vol 595 ◽

pp. 226-230 ◽

Cited By ~ 20

Author(s):

L.W. Veldhuizen ◽

C.H.M. van der Werf ◽

Y. Kuang ◽

N.J. Bakker ◽

S.J. Yun ◽

...

Keyword(s):

Thin Films ◽

Chemical Vapor Deposition ◽

Amorphous Silicon ◽

Vapor Deposition ◽

Silicon Germanium ◽

Hydrogenated Amorphous Silicon ◽

Chemical Vapor ◽

Hot Wire ◽

Amorphous Silicon Germanium ◽

Hydrogenated Amorphous

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Hydrogenated Amorphous Silicon Germanium Alloys Grown by the Hot-Wire Chemical Vapor Deposition Technique

MRS Proceedings ◽

10.1557/proc-507-447 ◽

1998 ◽

Vol 507 ◽

Cited By ~ 23

Author(s):

Brent P. Nelson ◽

Yueqin Xu ◽

D.L. Williamson ◽

Bolko Von Roedern ◽

Alice Mason ◽

...

Keyword(s):

Chemical Vapor Deposition ◽

Vapor Deposition ◽

Silicon Germanium ◽

Hydrogenated Amorphous Silicon ◽

Chemical Vapor ◽

Hot Wire ◽

Germanium Content ◽

Amorphous Silicon Germanium ◽

Hydrogenated Amorphous ◽

Gas Ratio

ABSTRACTWe successfully grow high-quality hydrogenated amorphous-silicon-germanium alloys (a-SiGe:H) by the hot-wire chemical-vapor deposition (HWCVD) technique using silane and germane gas mixtures. These alloys display electronic properties as good as those grown by the plasma-enhanced chemical-vapor deposition (PECVD) technique, when comparing materials with the same optical bandgaps. However, we grow materials with good electrical properties at high deposition rates—up to 40 Å/s, compared to 1–4 Å/s for PECVD materials. Our alloys exhibit similar trends with increasing Ge content to alloys grown by PECVD. The defect density, the dark conductivity, and the degree of nanostructural heterogeneity (as measured by small-angle X-ray scattering) all increase with increasing germanium content in the alloy. The nanostructural heterogeneity displays a sharp transition between 9 at.% and 14 at.% germanium. PECVD- grown a-SiGe:H alloys exhibit a similar transition at 20 at.% Ge. The photoconductivity and the ambipolar diffusion length of the alloys decrease with increasing germanium content. For a fixed silane-to-germane gas ratio, all material properties improve substantially when increasing substrate temperature (Tsub) from 220°C to 375°C. Increasing Tsub also narrows the optical bandgap and lowers the hydrogen content in the alloys for the same germane-to-silane gas ratio.

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

MRS Proceedings ◽

10.1557/proc-192-499 ◽

1990 ◽

Vol 192 ◽

Cited By ~ 1

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).

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