Monolithic β -Ga2O3 NMOS IC based on heteroepitaxial E-mode MOSFETs

In this Letter, we report on a monolithically integrated β-Ga2O3 NMOS inverter integrated circuit (IC) based on heteroepitaxial enhancement mode (E-mode) β-Ga2O3 metal-oxide-semiconductor field-effect transistors on low-cost sapphire substrates. A gate recess technique was employed to deplete the channel for E-mode operation. The E-mode devices showed an on-off ratio of ∼105 with a threshold voltage of 3 V. In comparison, control devices without the gate recess exhibited a depletion mode (D-mode) with a threshold voltage of −3.8 V. Furthermore, depletion-load NMOS inverter ICs were fabricated by monolithically integrating D- and E-mode transistors on the same substrate. These NMOS ICs demonstrated inverter logic operation with a voltage gain of 2.5 at VDD = 9 V, comparable with recent GaN and other wide-bandgap semiconductor-based inverters. This work lays the foundation for heteroepitaxial low-cost and scalable β-Ga2O3 ICs for monolithic integration with (ultra)wide bandgap Ga2O3 power devices.