β‑Ga₂O₃ Nanomembrane Negative Capacitance Field-Effect Transistors with Steep Subthreshold Slope for Wide Band Gap Logic Applications

Steep-slope β-Ga₂O₃ nanomembrane negative capacitance field-effect transistors (NC-FETs) are demonstrated with ferroelectric hafnium zirconium oxide in the gate dielectric stack. Subthreshold slope less than 60 mV/dec at room temperature is obtained for both forward and reverse gate-voltage sweeps with a minimum value of 34.3 mV/dec at the reverse gate-voltage sweep and 53.1 mV/dec at the forward gate-voltage sweep at V_DS = 0.5 V. Enhancement-mode operation with a threshold voltage of ∼0.4 V is achieved by tuning the thickness of the β-Ga₂O₃ membrane. Low hysteresis of less than 0.1 V is obtained. The steep-slope, low hysteresis, and enhancement-mode β-Ga₂O₃ NC-FETs are promising as an nFET candidate for future wide band gap complementary metal-oxide-semiconductor logic applications.