Barrier height values of Ni contacts to Mg-doped p-type GaN (p-GaN) were obtained from current–voltage measurements in this study. The induced deep level defect band through high Mg doping led to a reduction of the depletion layer width in the p-GaN near the interface and an increase in the probability of thermionic field emission. It also resulted in an increase in current flow under forward bias condition, which was not analyzed using the thermionic emission model. Further, the calculated barrier height value of Ni contacts to p-GaN using the thermionic field emission model is in good agreement with the value of 1.9 eV obtained from x-ray photoelectron spectroscopy measurements.
