Photovoltaically active p layers of amorphous silicon

Studies on amorphous silicon p-n diodes have shown that the p layers are photovoltaically active. Jsc of up to 3.4 mA/cm2 and Voc of 780 mV have been observed. Detailed quantum efficiency measurements were performed as a function of bias voltage, p-layer thickness, and boron doping. The data fit a simple depletion width model in which all photogenerated carriers created inside the depletion region are collected. An additional ‘‘reverse’’ barrier depletion width is assumed at the interface between the front transparent oxide electrode and the p layer to explain the results. A 10-nm-thick p layer typically used in p-i-n cells could collect up to 1 mA/cm2 if the electric field in the p layer is greater than 105 V/cm.