Improving Narrow Bandgap a-SiGe:H Alloys Grown by Hot-Wire Chemical Vapor Deposition

Yueqin Xu; B. P. Nelson; L. M. Gedvilas; R. C. Reedy

doi:10.1016/S0040-6090(03)00110-X

Improving Narrow Bandgap a-SiGe:H Alloys Grown by Hot-Wire Chemical Vapor Deposition

Yueqin Xu, B. P. Nelson, L. M. Gedvilas, R. C. Reedy

Materials, Chemical, and Computational Science Research Operations

National Renewable Energy Laboratory

Research output: Contribution to journal › Article › peer-review

19 Scopus Citations

Abstract

We have improved the electronic properties of narrow-bandgap (Tauc gap below 1.5 eV) amorphous-silicon germanium alloys (a-SiGe:H) grown by hot-wire chemical vapor deposition (HWCVD) by lowering the substrate temperature and deposition rate. Prior to this work, we were unable to grow a-SiGe:H alloys with bandgaps below 1.5 eV that had photo-to-dark conductivity ratios comparable with our plasma-enhanced CVD (PECVD) grown materials [B.P. Nelson et al., Mater. Res. Soc. Symp. 507 (1998) 447]. Decreasing the filament diameter from our standard configuration of 0.5 mm to 0.38 or 0.25 mm provides first big improvements in the photoresponse of these alloys. Lowering the substrate temperature from our previous optimal temperatures (T_sub starting at 435 °C) to at 250 °C provides additional photo-to-dark conductivity ratio increasing by two orders of magnitude for growth conditions containing 20-30% GeH₄ in the gas phase (relative to the total GeH₄+SiH₄ flow).

Original language	American English
Pages (from-to)	197-201
Number of pages	5
Journal	Thin Solid Films
Volume	430
Issue number	1-2
DOIs	https://doi.org/10.1016/S0040-6090(03)00110-X https://doi.org/10.1016/S0040-6090(03)00110-X
State	Published - 2003
Event	Proceedings of the Second International Conference on CAT-CVD - Denver, CO, United States Duration: 10 Sep 2002 → 13 Sep 2002

NREL Publication Number

NREL/JA-520-33125

Keywords

Amorphous-silicon germanium alloy
Filament
Optical bandgap
Photo-to-dark conductivity ratio
Photoresponse
Substrate
Tauc gap

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title = "Improving Narrow Bandgap a-SiGe:H Alloys Grown by Hot-Wire Chemical Vapor Deposition",

abstract = "We have improved the electronic properties of narrow-bandgap (Tauc gap below 1.5 eV) amorphous-silicon germanium alloys (a-SiGe:H) grown by hot-wire chemical vapor deposition (HWCVD) by lowering the substrate temperature and deposition rate. Prior to this work, we were unable to grow a-SiGe:H alloys with bandgaps below 1.5 eV that had photo-to-dark conductivity ratios comparable with our plasma-enhanced CVD (PECVD) grown materials [B.P. Nelson et al., Mater. Res. Soc. Symp. 507 (1998) 447]. Decreasing the filament diameter from our standard configuration of 0.5 mm to 0.38 or 0.25 mm provides first big improvements in the photoresponse of these alloys. Lowering the substrate temperature from our previous optimal temperatures (Tsub starting at 435 °C) to at 250 °C provides additional photo-to-dark conductivity ratio increasing by two orders of magnitude for growth conditions containing 20-30% GeH4 in the gas phase (relative to the total GeH4+SiH4 flow).",

keywords = "Amorphous-silicon germanium alloy, Filament, Optical bandgap, Photo-to-dark conductivity ratio, Photoresponse, Substrate, Tauc gap",

author = "Yueqin Xu and Nelson, {B. P.} and Gedvilas, {L. M.} and Reedy, {R. C.}",

year = "2003",

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AU - Nelson, B. P.

AU - Gedvilas, L. M.

AU - Reedy, R. C.

PY - 2003

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AB - We have improved the electronic properties of narrow-bandgap (Tauc gap below 1.5 eV) amorphous-silicon germanium alloys (a-SiGe:H) grown by hot-wire chemical vapor deposition (HWCVD) by lowering the substrate temperature and deposition rate. Prior to this work, we were unable to grow a-SiGe:H alloys with bandgaps below 1.5 eV that had photo-to-dark conductivity ratios comparable with our plasma-enhanced CVD (PECVD) grown materials [B.P. Nelson et al., Mater. Res. Soc. Symp. 507 (1998) 447]. Decreasing the filament diameter from our standard configuration of 0.5 mm to 0.38 or 0.25 mm provides first big improvements in the photoresponse of these alloys. Lowering the substrate temperature from our previous optimal temperatures (Tsub starting at 435 °C) to at 250 °C provides additional photo-to-dark conductivity ratio increasing by two orders of magnitude for growth conditions containing 20-30% GeH4 in the gas phase (relative to the total GeH4+SiH4 flow).

KW - Amorphous-silicon germanium alloy

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KW - Photo-to-dark conductivity ratio

KW - Photoresponse

KW - Substrate

KW - Tauc gap

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Improving Narrow Bandgap a-SiGe:H Alloys Grown by Hot-Wire Chemical Vapor Deposition

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Keywords

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