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

Research output: Contribution to journalArticlepeer-review

19 Scopus Citations


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).

Original languageAmerican English
Pages (from-to)197-201
Number of pages5
JournalThin Solid Films
Issue number1-2
StatePublished - 2003
EventProceedings of the Second International Conference on CAT-CVD - Denver, CO, United States
Duration: 10 Sep 200213 Sep 2002

NREL Publication Number

  • NREL/JA-520-33125


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


Dive into the research topics of 'Improving Narrow Bandgap a-SiGe:H Alloys Grown by Hot-Wire Chemical Vapor Deposition'. Together they form a unique fingerprint.

Cite this