Properties of hydrogenated amorphous silicon prepared by chemical vapor deposition from higher silanes

A review is given of the optical, electronic and device properties of hydrogenated amorphous silicon (a-Si:H) prepared by chemical vapor deposition (CVD) from higher order silanes. Prepared in this way, a-Si:H possesses a smaller energy gap than its counterpart prepared by glow discharge (GD) techniques, and thus is a potentially interesting material for photovoltaic solar energy conversion. Topics discussed are the deposition mechanism, hydrogen concentration and bonding, the optical energy gap, dark conductivity and photoconductivity, sub-bandgap absorption, the effect of hydrogen plasma treatment, doping properties, gap states, and photovoltaic devices.