Two Kelvin Operation of Ultrawide-Bandgap β-Ga₂O₃ FinFETs and Logic Inverter Integrated Circuits

Resilient extreme-temperature electronics are critical for applications ranging from quantum computing to space exploration. Ultrawide-bandgap (UWBG) β-Ga₂O₃ semiconductors are promising for operation across cryogenic and high-temperature regimes; however, their cryogenic performance remains insufficiently explored. Here, we demonstrate β-Ga₂O₃ transistor operation down to 2 K by exploiting Mott's variable-range hopping (VRH) conduction in impurity bands. The β-Ga₂O₃ FinFETs exhibit enhancement-mode behavior with a threshold voltage of 1.87 V, an ON/OFF current ratio exceeding 10⁶, and a subthreshold swing of 152 mV/dec at 2 K. Furthermore, a monolithic β-Ga₂O₃ inverter integrated circuit is realized, achieving a voltage swing of 4.88 V and a voltage gain of 28 at a 5 V supply with DC power dissipation of 0.13 μW at 2 K. Stable cryogenic performance arises from FinFET architecture and precise doping that enable VRH, consistent with a two-band transport model of the β-Ga₂O₃ channel, hence establishing β-Ga₂O₃ cryogenic electronics.