Characteristics of β-Ga2O3 MOSFETs on polycrystalline diamond via electrothermal modeling

Abstract

The integration of polycrystalline diamond (PCD) has been considered as a promising approach for overcoming the thermal management challenges in β-Gallium oxide (β-Ga2O3) metal-oxide-semiconductor field effect transistors (MOSFETs). This study investigates the coupled electrical and thermal characteristics of β-Ga2O3-on-diamond MOSFETs via electrothermal modeling. Results reveal that thicker diamond improves heat transfer efficiency with an optimal value of ∼100 μm by utilizing regions with higher thermal conductivity. The ambient temperature (Tamb) correlates negatively with the device temperature rise (ΔT) due to reduced electrical mobility and current density at elevated temperatures. Excellent electrical performance has been demonstrated for β-Ga2O3 MOSFETs, with a high saturation current density (Id,sat = 42.7 mA/mm) and a low specific on-resistance (RON,sp = 264.8 mΩ·mm2) at 300 K with Vg = −2 V and Vd = 20 V, along with a high on/off ratio (Ion/Ioff ∼ 1011) and a low subthreshold swing (SS = 83.3 mV/dec), making it highly suitable as a power switch. Comparative analysis with devices on other substrates (Si, SiC, and sapphire) highlights the exceptional carrier mobility and heat spreading capability benefited from the diamond substrate, especially at high power levels. Our TCAD-based fully-coupled electrothermal simulations provide comprehensive and accurate insights into the electrical and thermal performance of Ga2O3-based devices, offering guidance for the design and optimization of high-power devices.