In this study, the influence of HfO₂ interlayer thickness on the performance of heteroepitaxial α-Ga₂O₃ layer-based metal–insulator–semiconductor–insulator–metal (MISIM) ultraviolet photodetectors is examined. A thin HfO₂ interlayer enhances the interface quality and reduces the density of interface traps, thereby improving the performance of UVC photodetectors. The fabricated device with a 1 nm HfO₂ interlayer exhibited a significantly reduced dark current and higher photocurrent than a conventional metal–semiconductor–metal (MSM). Specifically, the 1 nm HfO₂ MISIM device demonstrated a photocurrent of 2.3 μA and a dark current of 6.61 pA at 20 V, whereas the MSM device exhibited a photocurrent of 1.1 μA and a dark current of 73.3 pA. Furthermore, the photodetector performance was comprehensively evaluated in terms of responsivity, response speed, and high-temperature operation. These results suggest that the proposed ultra-thin HfO₂ interlayer is an effective strategy for enhancing the performance of α-Ga₂O₃-based UVC photodetectors by simultaneously suppressing dark currents and increasing photocurrents and ultimately demonstrate its potential for stable operation under extreme environmental conditions.

We report a vertical $\beta $ -Ga₂O₃ Schottky barrier diode (SBD) enhanced with a ferroelectric aluminum scandium nitride (AlScN) field plate (FP). The FP SBD exhibits a reduced on-resistance ( ${R}_{\textsc{on}}\text {)}$ of 2.88–5.08 m $\Omega \cdot $ cm² and a breakdown voltage (BV) of 635–865 V, which is approximately $3.5\times $ higher than BV of the reference SBD ( ${R}_{\textsc{on}}$ : 3.16–6.15 m $\Omega \cdot $ cm²; BV: 210–243 V). Additionally, we showed that performance can be further improved by FP SBD that incorporates a 4-nm HfO₂ interlayer (IL) FP SBD, achieving ${R}_{\textsc{on}}$ of 3.07–5.59 m $\Omega \cdot $ cm² and a BV of 1115–1155 V. Electrical performance is assessed up to 550 K, while structural analysis confirms the first direct deposition of reactive sputtered ferroelectric AlScN on the $\beta $ -Ga₂O₃ epilayer. TCAD simulations verify the polarization field effect in these gains and also validate the electric field dispersion effect with increasing AlScN thickness. Consequently, the FP SBD delivered a significant improvement ( $\gt$ $10\times \text {)}$ , and the ILFP SBD delivered an improvement of ( $\gt$ $20\times \text {)}$ in Baliga’s figure of merits (BFOMs), highlighting its potential to advance Ga₂O₃-based power devices ’ performance.