2-Dimensional Ga2O3 Based Field Effect Transistor for Hydrogen Sensing Application

Abstract

β-phase gallium oxide (β-Ga2O3) has attracted a lot of interest for the applications of high-power electronics, gas sensors, and solar-blind photodetectors. β-Ga2O3 is an alternative semiconducting material for high-power and high-temperature devices due to a large bandgap energy of 4.9 eV and high critical breakdown field (> 8 MV/cm). The Baliga’s figure of merit is 3400, which is 4-10 times higher than those of GaN and SiC. Ga2O3 based devices is expected to be more efficient with reduced size and high level of integration because the theoretical on-state resistance is almost one order magnitude lower than those of GaN and SiC devices at the same breakdown voltage. When compared to GaN and SiC, single crystal Ga2O3 wafers are available at low cost with floating zone and the edge-defined film-fed growth methods. The monoclinic β-Ga2O3 is the most stable form among five different crystal phases of Ga2O3. The large lattice constant of 12.23 Å of β-Ga2O3 along [100] direction enables to achieve the facile cleavage of β-Ga2O3 crystal into 2-dimensional flake though β-Ga2O3 is not a Van der Waals material. The thin channel of Ga2O3 flake is beneficial to the FET (field effect transistor) type gas sensor. In this study, the fabrication of 2-dimensional β-Ga2O3 flake based field effect transistor and its hydrogen sensing characteristics for hydrogen sensor application will be presented.