Electrical transport properties of wafer-fused p-GaAs/n-GaN heterojunctions

GaAs/GaN pn heterojunction diodes have been fabricated by direct wafer fusion and characterized by capacitance-voltage (C-V) measurements and temperature dependent current-voltage (I-V) measurements. The wafer-fused pn diode showed a good rectifying behavior, but a small turn-on voltage was observed, which was attributed to defect-assisted tunneling-recombination. The flat-band voltage extracted from C-V is around 0.46 V, much smaller than the built-in voltage calculated for an ideal GaAs/GaN pn heterojunction. A band diagram including interface charge effects together with a possible energy barrier, stemming from a layer of disordered material at the fused GaAs/GaN interface, has been proposed to explain the experimental observations. (C) 2008 American Institute of Physics.