Characteristics of MgO/GaN gate-controlled metal–oxide– semiconductor diodes

Gate-controlled $n^{+}p$ metal–oxide–semiconductor diodes were fabricated in $\mathrm{p-}\mathrm{GaN}$ using MgO as a gate dielectric and ${\mathrm{Si}}^{+}$ implantation to create the $n^{+}$ regions. This structure overcomes the low minority carrier generation rate in GaN and allowed observation of clear inversion behavior in the dark at room temperature. By contrast, diodes without the $n^{+}$ regions to act as an external source of minority carriers did not show inversion even at measurement temperatures of 300 °C. The gated diodes showed the expected shape of the current–voltage characteristics, with clear regions corresponding to depletion and inversion under the gate. The MgO was deposited prior to the Si implantation and was stable during the activation annealing for the Si-implanted $n^{+}$ regions.