AlGaN/GaN E-mode MOS-HEMT Using Atomic-Layer-Deposited HfLaO x as Gate Dielectric

In this paper, we report GaN MOS-HEMTs with high quality atomic-layer-deposited HfLaO x as gate dielectric. The threshold voltage of the recessed gate MOS-HEMT can be enhanced from -6.2 V to 0.8 V. The E-mode GaN MOS-HEMT exhibits ideal subthreshold swing $\sim ~66$ mV/dec and high on-off ratio of $1.2\times 10^{10}.$ Conductance method has been applied to reveal interface trap density $D_{\mathrm {it}}$ distribution between high-k/III-N interface. Effective mobility of D-mode and E-mode MOS-HEMTs are $1958\,\mathrm{cm}^{2}/V \cdot\mathrm{s}$ and $1483\,\mathrm{cm}^{2}/\mathrm{V} \cdot \mathrm{s}$, respectively. A high breakdown voltage of 840 V was achieved, thanks to suppressed gate leakage. The specific on-resistance of E-mode device is 1.86 $\text{m}\omega \cdot \mathrm{cm}^{2}$, which results in high power figure of merit (BV 2 /R on,sp ) of 380 MW/cm 2 .