An 8-nm-thick Sn-doped polycrystalline β-Ga2O3 MOSFET with a “normally off” operation

Abstract

Monoclinic gallium oxide (β-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 β-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 β-Ga2O3 was determined to be 5.77 eV, which is larger than that of 100-nm-thick Sn-doped β-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 224 V (2.88 MV/cm). This ultrathin β-Ga2O3 layer could also be applied to fields other than power electronics, including displays, optical sensors, photocatalytic sensors, and solar cells.