Normally-Off p-Channel AlGaN/GaN/AlGaN MESFET With High Breakdown Voltage and Ultra-Low Interface State Density

In this work, a novel normally-off p-channel AlGaN/GaN/AlGaN Metal-Semiconductor field effect transistor (MESFET) with threshold voltage (
$\text{V}_{\text {TH}}$
) of −0.7 V is demonstrated. The state-of-the-art breakdown voltage of −198 V and breakdown electric field of 1 MV/cm are obtained for the fabricated MESFET with gate to drain distance of
$2~\mu \text{m}$
, owing to the high bandgap p-AlGaN layer. Moreover, the high-quality Schottky interface with ultra-low interface state density of 1.4-
$3.4\times 10^{{11}}$
cm
$^{-2} \cdot $
eV−1, which is extracted by conductance method, contributes to the negligible hysteresis effect of the ten-consecutive dual-swept I-V curves. The novel AlGaN/GaN/AlGaN p-MESFETs with high breakdown electric field and stable I-V characteristics show a great potential for next-generation GaN integrated circuit.