$beta$-Ga$_2$O$_3$ Nano-membrane Negative Capacitance Field-effect Transistor with Steep Subthreshold Slope for Wide Bandgap Logic Applications

Steep-slope $beta$-Ga$_2$O$_3$ nano-membrane negative capacitance field-effect transistors (NC-FETs) are demonstrated with ferroelectric hafnium zirconium oxide in 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 reverse gate voltage sweep and 53.1 mV/dec at forward gate voltage sweep at $V_{DS}$=0.5 V. Enhancement-mode operation with threshold voltage ~0.4 V is achieved by tuning the thickness of $beta$-Ga$_2$O$_3$ membrane. Low hysteresis of less than 0.1 V is obtained. The steep-slope, low hysteresis and enhancement-mode $beta$-Ga$_2$O$_3$ NC-FETs are promising as nFET candidate for future wide bandgap CMOS logic applications.