Thermodynamic Studies of \b{eta}-Ga2O3 Nanomembrane Field-Effect Transistors on a Sapphire Substrate

TL;DR

This study demonstrates that using a sapphire substrate significantly reduces self-heating in eta-Ga2O3 nanomembrane FETs, leading to higher current density and improved device performance for power electronics.

Contribution

The paper introduces the use of sapphire substrates to mitigate self-heating in eta-Ga2O3 FETs, enhancing thermal management and device performance.

Findings

Temperature rise is reduced by a factor of 3 on sapphire substrates.

Thermal resistance on sapphire is less than one-third of that on SiO2/Si.

Maximum drain current density increases by 70% on sapphire substrates.

Abstract

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 \b{eta}-Ga2O3 on insulator field-effect transistors. Here, we demonstrate that by utilizing a higher thermal conductivity sapphire substrate rather than a SiO2/Si substrate, the temperature rise above room temperature of \b{eta}-Ga2O3 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 SiO2/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 SiO2/Si substrate due to reduced self-heating. Integration of \b{eta}-Ga2O3 channel on a higher thermal conductivity substrate opens a new route to address the low thermal conductivity issue of \b{eta}-Ga2O3 for power electronics applications.