Structural investigation of hydrogenated amorphous silicon germanium alloys

Hydrogenated amorphous silicon germanium (a-Si/sub 1-x/Ge/sub x/:H) alloys for solar cells are investigated to clarify the relation between microstructures and photoelectric properties. Medium-range order alloy structures are investigated using small-angle X-ray scattering with the aid of other techniques. A decrease in the densities of microstructures caused by (SiH/sub 2/)/sub n/, SiH/sub 3/, and SiH/sub 2/ is shown to be effective in improving the photoelectric properties in the Si-rich region. It is also shown that a-Si:H and a-Ge:H have a domain and wall-type microstructure. At around x=0.5, alloys are found to assume a fractal structure. This phenomenon seems to relate closely to drastic quality deterioration at E/sub g/<1.4 eV.<
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