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In this article, we have proposed and analyzed a novel $\beta $ -phase gallium oxide ( $\beta $ -Ga2O3) metal–oxide–semiconductor field-effect transistor (MOSFET) with double drift layers (DDLs) located in the gate to drain region. This device has a highly doped drift (HDD) layer that is positioned below a lowly doped drift layer, which are connected in parallel. The HDD is located at a distance ( ${d}$ ) from the gate metal to ensure optimal breakdown performance. We extensively investigated how the doping concentration and thickness of the HDD, with both small and large ${d}$ values, affect the device’s electrical characteristics. Our simulations revealed that the proposed device achieved a decent power figure-of-merit (PFOM) of 582.0 and 461.2 MW/cm2 at ${d}$ values of 0.5 and $3.5~\mu \text{m}$ , respectively. Compared to the control device with single drift layer, the designed construction achieved an excellent PFOM and reduced specific ON-resistance ( ${R} _{{\text {on},\text {sp}}}$ ), while maintaining an unaltered or appreciable breakdown voltage ( ${V} _{{\text {br}}}$ ). This proposed structure provides a new way to achieve high performance for $\beta $ -Ga2O3 MOSFETs.

We report a method for improving the electrical performance of Pt/ $\beta $ -Ga2O3 Schottky barrier diodes (SBDs) through surface pretreatment using low-temperature O2 gas annealing. We found that subjecting the $\beta $ -Ga2O3 surface to 5 min of O2 gas pretreatment at 400 °C before anode metal deposition resulted in an 18% increase in breakdown voltage ( ${V}_{\text {br}}{)}$ and a 42% improvement in power figure-of-merit (PFOM) compared to control devices. X-ray photoelectron spectroscopy (XPS) analysis revealed that the O2 gas pretreatment caused the oxidation of the Ga $^{{2}+}$ states on the surface, which increased the Schottky barrier height ( ${q}\phi _{\text {b}}{)}$ and improved the ideality factor of the SBDs. However, when the pretreatment time was extended to 15 min, we observed the evidence of the reduction process of the oxidized Ga $^{{2}+}$ , which resulted in a degraded ${V}_{\text {br}}$ and a reduced ${q}\phi _{\text {b}}$ of the SBDs. Overall, our findings suggest that low-temperature O2 gas annealing is a promising approach for engineering the Schottky interface of $\beta $ -Ga2O3 SBDs and improving their performance.

In this letter, we report on a unique positive bias stress (PBS) instability observed in the heterogeneous Ga2O3-on-SiC (GaOSiC) metal-oxide-semiconductor field-effect transistor (MOSFET). The Ga2O3 layer in the GaOSiC MOSFET, which was fabricated using the ion implantation process, still contains hydrogen (H), leading to significantly different threshold voltage ( ${V}_{\text {TH}}{)}$ shifts and on-resistance ( ${R}_{\text {ON}}{)}$ variations compared to transistors on Ga2O3 bulk under PBS. During the initial several tens of seconds of PBS, the GaOSiC MOSFET exhibits a normal positive ${V}_{\text {TH}}$ shift, resulting from the capture of some electrons in the channel by border traps in the gate dielectric and interface traps. However, as the PBS time increases, the ${V}_{\text {TH}}$ of the GaOSiC transistor starts to shift in the negative direction. This can be attributed to the generation of shallow donors under PBS, with the presence of H, resulting in an increased carrier density ( ${n}_{\text {e}}{)}$ in the Ga2O3 channel. The increased ${n}_{\text {e}}$ also leads to an improvement in drain current and a reduction in ${R}_{\text {ON}}$ of the GaOSiC MOSFET during long-term PBS. Our work provides new insights into the PBS instability of heterogeneous GaOSiC MOSFETs, particularly for high-power applications.