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Articles you may be interested inDetermination of hydrogenated amorphous silicon electronic transport parameters and density of states using several photoconductivity techniques

The first experimental evidence for a thermal-equilibrium defect density in undoped hydrogenated amorphous silicon, a metastable material, is presented. The defect density is in thermal equilibrium at temperatures above 200 °C; the defects measured at room temperature are largely those frozen in during cooling from the equilibrium regime. Rapid quenching reversibly increases defect density. The defect density can be reversibly decreased by shunting of the defect-generation process during cooling. This latter technique has important implications for a-Si:H-based solar cells.

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The properties of a-(Si, Ge):H, F alloys prepared by glow discharge deposition from SiH4 and GeF4 are described. The measured IR absorption spectra, sub-gap absorption spectra, dark conduction activation energies, carrier drift mobilities and deep trapping lifetimes of these alloys are similar to those of alloys prepared from SiF4, GeF4, and H2. However, they have over an order of magnitude lower photoconductivity over most of the composition range. Infrared absorption measurements indicate that these alloys have a fluorine content less than 1.5 at.% and a Si-H2 content that increases with germanium concentration.