Direct Correlation Between Film Structure and Solar Cell Efficiency for HWCVD Amorphous Silicon Germanium Alloys
The film structure and H bonding of high deposition rate a-SiGe:H i-layers, deposited by HWCVD and containing {approx}40 at.% Ge, have been investigated using deposition conditions which replicate those used in n-i-p solar cell devices. Increasing the germane source gas depletion in HWCVD causes not only a decrease in solar cell efficiency from 8.64% to less than 7.0%, but also an increase in both the i-layer H preferential attachment ratio (PA) and the film microstructure fraction (R{sup {sq_bullet}}). Measurements of the XRD medium range order over a wide range of germane depletion indicate that this order is already optimum for the HWCVD i-layers, suggesting that energetic bombardment of a-SiGe:H films may not always be necessary to achieve well ordered films. Preliminary structural comparisons are also made between HWCVD and PECVD device layers.
- Research Organization:
- National Renewable Energy Lab. (NREL), Golden, CO (United States)
- Sponsoring Organization:
- USDOE Office of Solar Energy Technologies Program
- DOE Contract Number:
- AC36-08GO28308
- OSTI ID:
- 1023708
- Journal Information:
- Thin Solid Films, Vol. 517, Issue 12, 2009; ISSN 0040-6090
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
AMORPHOUS STATE
AUGMENTATION
BONDING
CHEMICAL BONDS
CHEMICAL VAPOR DEPOSITION
CORRELATIONS
DEPOSITION
EFFICIENCY
FILMS
GERMANIUM
GERMANIUM ALLOYS
GERMANIUM HYDRIDES
HYDROGEN
LAYERS
MICROSTRUCTURE
SILICON
SILICON SOLAR CELLS
SOLAR CELLS
X-RAY DIFFRACTION
Solar Energy - Photovoltaics