Versatile Contact Engineering on β-Ga2O3 Using EGaIn for Schottky Diodes and MESFET Applications

Beta gallium oxide (β-Ga₂O₃) has emerged as a promising ultrawide bandgap n-type semiconductor for large-area circuit integration and high-power device applications in the field of 5G and AI technology. However, β-Ga₂O₃ has a critical problem in Ohmic contact formation using a traditional metallization method. In this study, a low-temperature fabrication strategy is successfully demonstrated of an Ohmic contact electrode, employing eutectic gallium indium (EGaIn) liquid metal on β-Ga₂O₃ active channel material for Schottky diode circuit and metal semiconductor field effect transistor (MESFET) applications. The selective screen-printing of Ohmic and rectifying contacts enables monolithic integration of symmetric and asymmetric device architectures, including source/drain electrodes, Schottky diodes, and FETs without additional post-thermal annealing and etching processes. The β-Ga₂O₃/Au Schottky diodes exhibit good rectifying properties of a current on/off ratio of 10⁷ and an ideality factor (η) of 1.63, while the MESFET devices demonstrate a drain current on/off ratio of ≈3.1 × 10⁶.