Electrical characteristics of amorphous GaAs-n-crystalline Si heterojunctions

Capacitance-voltage (C-V) characteristics and temperature dependence of current density-voltage (J-V) characteristics of as-grown amorphous gallium arsenide (a-GaAs) thin film heterojunctions formed on n-type crystalline silicon (c-Si(n)) have been measured. It has been found that the depletion layer of a-GaAs-c-Si(n) junction spreads in the c-Si side. The forward current, for bias voltages less than 0.4 V, shows voltage and temperature dependence expressed as exp ( − Eaf/kT) exp (AV), where Eaf and A are constants independent of voltage and temperature. This current may be ascribed to a multi-tunnelling capture-emission phenomena. The reverse current is proportional to exp( −Ear/kT)(V)12, where Ear is a constant. This current is probably limited by a generation process.