2D Amorphous GaO_X Gate Dielectric for -Ga₂O₃ Field-Effect Transistors

Appropriate gate dielectrics mustbe identified to fabricatemetal-insulator-semiconductorfield-effect transistors (MISFETs); however, this has been challengingfor compound semiconductors owing to the absence of high-quality nativeoxides. This study uses the liquid-gallium squeezing technique tofabricate 2D amorphous gallium oxide (GaOX) with a highdielectric constant, where its thickness is precisely controlled atthe atomic scale (monolayer, & SIM;4.5 nm; bilayer, & SIM;8.5nm). Beta-phase gallium oxide (& beta;-Ga2O3) with an ultrawide energy bandgap (4.5-4.9 eV) has emergedas a next-generation power semiconductor material and is presentedhere as the channel material. The 2D amorphous GaOX dielectricis combined with a & beta;-Ga2O3 conductingnanolayer, and the resulting & beta;-Ga2O3 MISFETis stable up to 250 & DEG;C. The 2D amorphous GaOX is oxygen-deficient,and a high-quality interface with excellent uniformity and scalabilityforms between the 2D amorphous GaOX and & beta;-Ga2O3. The fabricated MISFET exhibits a wide gate-voltageswing of approximately +5 V, a high current on/off ratio, moderatefield-effect carrier mobility, and a decent three-terminal breakdownvoltage (& SIM;138 V). The carrier transport of the Ni/GaOX/& beta;-Ga2O3 metal-insulator-semiconductor(MIS) structure displays a combination of Schottky emission and Fowler-Nordheim(F-N) tunneling in the high-gate-bias region at 25 & DEG;C,whereas at elevated temperatures it shows Schottky emission and F-Ntunneling in the low- and high-gate-bias regions, respectively. Thisstudy demonstrates that a 2D GaOX gate dielectric layercan be produced and incorporated into an active channel layer to forman MIS structure at room temperature (& SIM;25 & DEG;C), which enablesthe facile fabrication of MISFET devices.