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

Area of Science:

• Materials Science
• Semiconductor Physics
• Electronics Engineering

Background:

• Extreme-temperature electronics are crucial for advanced applications like quantum computing and space exploration.
• Ultrawide-bandgap (UWBG) β-Ga₂O₃ shows potential for high and cryogenic temperature operation, but its low-temperature performance is understudied.

Purpose of the Study:

• To investigate and demonstrate the cryogenic performance of β-Ga₂O₃ transistors.
• To explore the underlying conduction mechanisms in β-Ga₂O₃ at extremely low temperatures.

Main Methods:

• Fabrication and characterization of β-Ga₂O₃ FinFETs.
• Electrical measurements of transistor performance down to 2 K.
• Analysis of conduction mechanisms using Mott's variable-range hopping (VRH) model.

Main Results:

• Demonstrated enhancement-mode β-Ga₂O₃ FinFET operation at 2 K with a threshold voltage of 1.87 V and an ON/OFF ratio >10⁶.
• Achieved a subthreshold swing of 152 mV/dec at 2 K.
• Realized a monolithic β-Ga₂O₃ inverter circuit with a voltage gain of 28 at 5 V supply and low power dissipation (0.13 μW) at 2 K.

Conclusions:

• Stable cryogenic performance of β-Ga₂O₃ FinFETs is attributed to the device architecture and precise doping enabling VRH.
• The findings establish β-Ga₂O₃ as a viable material for cryogenic electronics, consistent with a two-band transport model.