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.