High-Voltage β-Ga₂O₃ RF MOSFETs With a Shallowly-Implanted 2DEG-Like Channel

We report radio-frequency (RF) MOSFETs with a two-dimensional-electron-gas-like (2DEG-like) channel formed at the $\beta $ -Ga ₂ O ₃ surface through the low-energy implantation of Si and rapid thermal activation process. The shallowly implanted channel exhibits a strong electron confinement near surface with a high sheet concentration of ${3}.{2}\times {10} ^{{13}}$ cm ⁻³ . With the high scaling of gate length ( ${L}_{\text {G}}{)}$ , the current cut-off frequency ( ${f}_{\text {T}}{)}$ and maximum oscillation frequency ( ${f}_{\text {max}}{)}$ were inversely proportional to ${L}_{\text {G}}$ along with a high electron saturation velocity of ${2}.{7}\times {10} ^{{6}}$ cm/s. The device with a ${L}_{\text {G}}$ of $0.15 ~\mu \text{m}$ demonstrates a high ${f}_{\text {T}}$ of 29 GHz and ${f}_{\text {max}}$ of 35 GHz, whilst preserving the high-voltage operation capability with a drain-to-source breakdown voltage ( $BV_{\text {DS}}{)}$ of 193 V. RF performance was verified by the power amplifying capability with a maximum power gain of 7 dB at 2 GHz for the device with ${L}_{\text {G}}$ of $0.5~\mu \text{m}$ .