BV > 3 kV/VTH = 3.5 V Normally-Off Al0.6Ga0.4N MOSFET With Recessed-Gate and Ferroelectric Gate Dielectric

This letter reports on the demonstration of recessed-gate ultra-wide bandgap semiconductor Al0.6Ga0.4N MOSFET with Hf0.5Zr0.5O2 (HZO) ferroelectric charge storage dielectric structure. A positive threshold voltage ( $\text{V}_{\text {TH}}$ ) of 3.550 V and maximum gate swing of 15 V is achieved due to the trapped electrons induced by remnant polarization of HZO in gate stack. The Al0.6Ga0.4N MOSFET exhibits a specific on-resistance ( $\text{R}_{\text {on,sp}}$ ) of ${17.8} \text {m}~\Omega \cdot \text {cm}^{{2}}$ . Moreover, an 840 V breakdown voltage (BV) is obtained with a gate-to-drain ( $\text{L}_{\text {gd}}$ ) length of $2 ~\mu \text{m}$ , indicating an average breakdown electric field ( $\text{E}_{\text {av}}$ ) beyond 4 MV/cm. In addition to the high $\text{E}_{\text {av}}$ , a high BV > 3 kV is also derived on a transistor with $\text {L}_{\text {gd}} = {8}\,\,\mu \text {m}$ , translating to a power figure-of-merit (P-FOM=BV2/ $\text{R}_{\text {on,sp}}$ ) of 208 MW/cm2. These high device performances indicate a great potential of Al-rich E-mode AlGaN MOSFET for future high-power applications.