Vertical Al2O3/GaN MOS capacitors with PEALD-GaO<i>x</i> interlayer passivation

In this Letter, we report high-quality vertical GaN metal–oxide–semiconductor (MOS) capacitors with sulfur passivation and a plasma-enhanced atomic layer deposition -grown GaOx interlayer, exhibiting a low interface trap density (Dit) of ∼8 × 1010 cm−2 eV−1 and a low frequency-dependent flatband voltage shift [ΔVFB (f)] of ∼20 mV (from 1 kHz to 1 MHz). The introduction of the GaOx interlayer effectively suppresses the leakage current (from ∼10−3 to ∼10−6 A/cm2 under 10 V positive bias) and passivates nitrogen/oxygen-related vacancies and dangling bonds. The demonstrated controllable and low-destructive passivation technique provides the insights and methodologies for the fabrication of high-performance GaN MOS structure-based devices.