Thermodynamic Studies of β-Ga(2)O(3) Nanomembrane Field-Effect Transistors on a Sapphire Substrate

[Image: see text] The self-heating effect is a severe issue for high-power semiconductor devices, which degrades the electron mobility and saturation velocity, and also affects the device reliability. On applying an ultrafast and high-resolution thermoreflectance imaging technique, the direct self-heating effect and surface temperature increase phenomenon are observed on novel top-gate β-Ga(2)O(3) on insulator field-effect transistors. Here, we demonstrate that by utilizing a higher thermal conductivity sapphire substrate rather than a SiO(2)/Si substrate, the temperature rise above room temperature of β-Ga(2)O(3) on the insulator field-effect transistor can be reduced by a factor of 3 and thereby the self-heating effect is significantly reduced. Both thermoreflectance characterization and simulation verify that the thermal resistance on the sapphire substrate is less than 1/3 of that on the SiO(2)/Si substrate. Therefore, maximum drain current density of 535 mA/mm is achieved on the sapphire substrate, which is 70% higher than that on the SiO(2)/Si substrate due to reduced self-heating. Integration of β-Ga(2)O(3) channel on a higher thermal conductivity substrate opens a new route to address the low thermal conductivity issue of β-Ga(2)O(3) for power electronics applications.