Electrical characterization of n-amorphous/p-crystalline silicon heterojunctions

n-type amorphous silicon on p-type crystalline silicon heterojunction diodes were fabricated and electrically characterized. The a-Si:H film was deposited by plasma enhanced chemical vapor deposition. Electrical properties were investigated by capacitance-voltage and current-voltage measurements at different temperatures. The capacitance-voltage results confirm an abrupt heterojunction. Current-voltage characteristics show good rectifying properties (50000:1 at +/-0.5 V). A detailed analysis of transport mechanisms was developed in order to establish a unified model of conduction. Two carrier transport mechanisms are believed to be at the origin of the forward current. At low bias voltage (V<0.4 V), the current is determined by recombination at the amorphous side of the space charge region, while at higher voltages (V>0.6 V), the current becomes space charge limited. (C) 1996 American Institute of Physics.