Optical and electronic properties of microcrystalline silicon as a function of microcrystallinity

Journal Article · Tue Feb 15 04:00:00 EST 2000 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.372108· OSTI ID:20215281

Han, Daxing ^[1]; Yue, Guozhen ^[1]; Lorentzen, J D ^[1]; Lin, Jing ^[1]; Habuchi, H ^[2]; Wang, Qi ^[3]

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1. Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3255 (United States)
2. Gifu National College of Technology, Sinsei-cho, Motosu-gun, Gifu, 501-0495, (Japan)
3. National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)

Films were prepared by hot wire chemical vapor deposition at {approx}240 degree sign C with varied hydrogen dilution ratios R=H{sub 2}:SiH{sub 4} from 1 to 20. The optical and electronic properties as a function of microcrystallinity were studied. We found: (a) At low H dilution R{<=}2, there is no measurable crystallinity by Raman spectroscopy and x-ray diffraction in the a-Si:H matrix, but an optical absorption peak at {approx}1.25 eV appears; when R=2, the film shows the lowest subgap absorption, the highest photosensitivity, and the largest optical gap. (b) When R{>=}3, the c-Si phase is measurable by Raman and a low-energy photoluminescence (PL) band (0.84-1.0 eV) appears in addition to the high-energy band (1.3-1.4 eV). Meanwhile, all the absorption spectra show a featureless line shape. (c) An energy redshift is observed for both PL peaks as the film grows thicker. Finally, (d) the conductivity activation energy first decreases from 0.68 to 0.12 eV, then increases with increasing microcrystallinity. A mode of two sets of energy bands of electronic states for these two-phase materials is suggested. (c) 2000 American Institute of Physics.

• OSTI ID: 20215281
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 4 Vol. 87; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ABSORPTION SPECTRA
ELECTRONIC STRUCTURE
EXPERIMENTAL DATA
HYDROGEN ADDITIONS
MICROSTRUCTURE
PHOTOLUMINESCENCE
RAMAN SPECTRA
SILICON
THIN FILMS
X-RAY DIFFRACTION