An 8-nm-Thick Sn-Doped β-Ga₂O₃ MOSFET with a Normally-Off Operation

Monoclinic gallium oxide (<i>β</i>-Ga₂O₃) has attracted the interest of the scientific community due to its application in power electronics. Power electronics that need to handle a high voltage often uses a “normally off” device with a positive threshold voltage due to its fail-safe operation and its simple system architecture. In this work, 8-nm-thick Sn-doped polycrystalline <i>β</i>-Ga₂O₃ thin films were investigated as a channel material for power electronics, and their properties were characterized. The optical bandgap of the 8-nm-thick Sn-doped <i>β</i>-Ga₂O₃ was determined to be 5.77 eV, which is larger than that of 100-nm-thick Sn-doped <i>β</i>-Ga₂O₃ due to the quantum confinement effect. The developed back-gated device demonstrated normally off behavior and exhibited a voltage handling capacity as high as 224V (2.88 MV/cm). Technology computer-aided design (TCAD) simulations is performed to understand the <i>V</i>_th shift behavior for the doping concentration and film thickness. This ultrathin <i>β</i>-Ga₂O₃ layer could also be applied to fields other than power electronics, including displays, optical sensors, photocatalytic sensors, and solar cells.