The preparation conditions for the deposition of hydrogenated amorphous silicon-carbon alloys (a-SiC:H) from a glow-discharge plasma have been systematically scanned by changing the starting-gas materials as well as the starting gas to hydrogen dilution ratio. A highly photosensitive alloy showing a photoconductivity to dark conductivity ratio of 107 at a band gap of 2.0 eV was prepared under optimized conditions.

The role of hydride coverage in surfacelimited thinfilm growth of epitaxial silicon and germanium Equilibrium surface hydrogen coverage during silicon epitaxy using SiH4Electronic surface changes induced in silicon by hydrogen, oxygen, and cesium coverages

We report and interpret two groups of experiments on the role that hydrogen plays in the formation of silicon microcrystals. We show that the growth of singlecrystal Si by molecular beam epitaxy at 475°C is disrupted by H2, which induces the formation of microcrystals. In crystallization experiments of non-hydrogenated a-Si and of hydrogenated a-Si:H on a hot stage in a transmission electron microscope, hydrogen facilitates the nucleation of crystallites. We explain our observations with a substantial reduction of the grain boundary energy by hydrogen.

Hydrogen in undoped, unalloyed microcrystalline silicon (μc-Si:H) has been investigated with secondary-ion mass spectrometry (SIMS), Raman spectroscopy, infrared absorption spectroscopy, and nuclear magnetic resonance (NMR). The samples were grown by plasma-enhanced chemical vapor deposition with hydrogen to silane dilution ratios (H2:SiH4) ranging from 0:1 to 98:1. Microcrystallinity is obtained for dilution ratios of 20:1 and greater. The hydrogen concentration is shown to depend nonmonotonically on the degree of hydrogen dilution. The H concentration in the films decreases with dilution for ratios from 0:1 to 10:1 and then increases with greater dilution. This dependence on dilution is established with both NMR and SIMS and suggests the existence of competing processes in the incorporation of hydrogen during deposition. It is further observed that the formation of microcrystallites is accompanied by the appearance of both higher order silicon hydrides and large concentrations of unbound molecular hydrogen.

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