Carrier Transport Mechanisms of a-GaAs/ n-Si Heterojunctions

Heterojunctions have been fabricated of p-type amorphous gallium arsenide (a-GaAs) thin films onto n-type silicon (n-Si) single crystals using thermal evaporation method. Current density-voltage and capacitance-voltage measurements have been performed to determine the electrical properties of the structures. Rectifying current involves tunneling and is explained by a multi-tunneling capture-emission model. The reverse current is limited by the carrier generation process. The capacitance-voltage behavior indicates an abrupt interface with a main-band discontinuity of 0.25 eV occurs in the valance band.