Current transport mechanism of p-GaN Schottky contacts

Abstract

Transient measurements of $\mathrm{I–V}$ and depletion layer capacitance were conducted to clarify the leaky current flow mechanism in Ni Schottky contacts formed on Mg-doped $\mathrm{p-}\mathrm{GaN}.$ We found that carrier capture and emission from acceptor-like deep level defects cause depletion layer width ${\mathrm{(W}}_{\mathrm{dep}})$ to vary significantly. Upon ionization of the defects by white light, which results in small $W_{\mathrm{dep}},$ current can go through the Schottky barrier and a leaky $\mathrm{I–V}$ curve is observed. Upon filling by current injection, $W_{\mathrm{dep}}$ becomes larger and the large original Schottky barrier height is seen. The time constant of carrier emission is as long as ${\text{8.3×10}}^3 \min .$