Microstructure of Amorphous-Silicon-Based Solar Cell Materials by Small-Angle X-Ray Scattering; Final Subcontract Report: 6 April 1994 - 30 June 1998
- Department of Physics: Colorado School of Mines
This report describes work performed to provide details of the microstructure in high-quality hydrogenated amorphous silicon and related alloys for the nanometer size scale. The materials studied were prepared by current state-of-the-art deposition methods, as well as new and emerging deposition techniques. The purpose was to establish the role of microstructural features in controlling the opto-electronic and photovoltaic properties. The approach centered around the use of the uncommon technique of small-angle X-ray scattering (SAXS), which is highly sensitive to microvoids and columnar-like microstructure. Nanovoids of H-rich clusters with 1 to 4 nm sizes in a-Si:H at the 1 vol.% level correlate with poor solar-cell and opto-electronic behavior. Larger-scale features due either to surface roughness or residual columnar-like structures were found in present state-of-the-art device material. Ge alloying above about 10 to 20 at.% typically leads to significant increases in heterogeneity , and this has been shown to be due in part to non-uniform Ge distributions. Ge additions also cause columnar-like growth, but this can be reduced or eliminated by enhanced ion bombardment during growth. In contrast, C alloying typically induces a random nanostructure consisting of a narrow size distribution of 1-nm-sized objects with a high density, consistent with the notably poorer opto-electronic behavior of these alloys.
- Research Organization:
- National Renewable Energy Lab. (NREL), Golden, CO (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- AC36-83CH10093
- OSTI ID:
- 14403
- Report Number(s):
- NREL/SR-520-25844; TRN: US200311%%2
- Resource Relation:
- Other Information: Supercedes report DE00014403; PBD: 8 Dec 1998; PBD: 8 Dec 1998
- Country of Publication:
- United States
- Language:
- English
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