RF sputtered gold-amorphous silicon Schottky-barrier diodes

Gold Schottky-barrier diodes formed on reactively sputtered amorphous silicon thin films have been investigated. Device forward I-V characteristics are well modeled as a Schottky diode in series with a temperature activiated series resistor. At 300 K, the forward current indicates a diode correction factor of 1.4 and a saturation current of 5.8 x 10 to the -10th A/sq cm. The metal-semiconductor barrier height is 0.93 eV. Capacitance versus frequency measurements indicate a depletion region thickness of 3000 A. In the depletion region, the mobility-lifetime products are estimated to be of the order of 5 x 10 to the -11th sq cm/V which is substantially less than the value of 10 to the -7th sq cm/V in the quasi-neutral region. It is suggested that deep gap states are responsible for this difference. Carrier recombination in the depletion region limits the photovoltaic performance.