Integrated monolithic inverter using gate-recessed gan-based enhancement-mode and depletion-mode metal-oxide-semiconductor high-electron mobility transistors

The integrated monolithic inverters constructed by GaN-based gate-recessed enhancement mode and depletion mode metal-oxide-semiconductor high-electron mobility transistors (MOSHEMTs) were fabricated using the photoelectrochemically (PEC) etched-gate recessed structure and the LiNbO₃ ferroelectric gate insulator deposited using the pulsed laser deposition system. Instead of the typical tuning gate width, to control the static voltage transfer characteristics but still keep the minimized matched area of the monolithic inverters, the drain-source current was adjusted by controlling the PEC-etched AlGaN thickness of the load-type depletion mode MOSHEMTs using the PEC etching method. Consequently, the drain-source current ratio β of the enhancement mode MOSHEMTs and the depletion mode MOSHEMTs in the monolithic inverters could be adjusted. When the β value was set at 25 and the monolithic inverters operated at V_DD = 5 V, the output swing, the high noise margin and the low noise margin were 4.86 V, 1.88 V, and 1.62 V, respectively, for changing input voltage from 0 V to 5 V. From the experimental voltage transfer characteristics, the monolithic inverters with β = 25 could operate as high performance unskewed inverters.