Large-Area In-Situ Oxide, GaN Interlayer-Based Vertical Trench MOSFET (OG-FET)

We present a large-area in-situ oxide, GaN interlayer-based vertical trench MOSFET (OG-FET) with a metal organic chemical vapor deposition regrown 10-nm unintentional-doped-GaN interlayer as the channel and 50-nm in-situ Al 2 O 3 as the gate dielectric. The threshold voltage of the device on bulk GaN substrate was 1 V measured at $\text{I}_\mathrm {on}/\text{I}_\mathrm {off}= 10^{7}$ . The OG-FET with an area scaled to 0.2 mm 2 demonstrated a breakdown voltage ( $\text{V}_\mathrm {BR}$ ) of 320 V and an on-state resistance ( $\text{R}_\mathrm {on}$ ) of $3.8~\Omega $ (specific on-state resistance: $\text{R}_\mathrm {on,sp}= 7.6\,\,\text{m}\Omega \,\,\cdot $ cm 2 ). For the single unit cell OG-FET from the same sample, $\text{V}_\mathrm {BR}$ was as high as 700 V (measured at $\text{V}_\mathrm {GS}=-10$ V), corresponding to a breakdown electric field of 1.4 MV/cm and $\text{R}_\mathrm {on,sp}$ of 0.98 $\text{m}\Omega ~\cdot $ cm 2 . On our control sample, which was grown on sapphire substrate, a 1-A current was measured as well. These results show the potential of the OG-FET in power conversion applications.