【International Papers】β-Ga₂O₃ Interlayer-Based Vertical Trench Power MOSFET With Fast-Switching Performance at High Temperatures

      Researchers from the University of Idaho have published a dissertation titled "Simulation of E-Mode β-Ga₂O₃ Interlayer-Based Vertical Trench Power MOSFET With Fast-Switching Performance at High Temperatures" in IEEE Access.

Background

      The power electronics market based on wide-bandgap (WBG) semiconductors, such as SiC and GaN, is growing significantly due to the surging needs across various industry applications, such as renewable energy, motor control, hybrid or electric vehicles, and aerospace. The main drawback of WBG semiconductors is their relatively high manufacturing cost compared to Si. An emerging alternative WBG semiconductor material is beta-phase gallium oxide (β-Ga₂O₃). As a candidate of ultra-wide bandgap (UWBG) semiconductor material, β-Ga2O3 has a large bandgap of ∼ 4.8 eV, lower cost of large-size bulk crystals than SiC and GaN, larger Baliga’s figure of merit than SiC and GaN and low intrinsic carrier concentration for high-temperature stability. The superior material properties of β-Ga₂O₃ have garnered extensive research attention in high-power and high-temperature applications in the past decade. The primary vertical transistors currently being developed with β-Ga₂O₃ include FinFETs, current aperture vertical MOSFETs (CAVETs) and U-shaped MOSFETs (UMOSFETs).

Abstract

      In this paper, an interlayer-based vertical trench power β-Ga₂O₃ MOSFET with nitrogen-doped current blocking layers (CBLs) is designed and simulated in Sentaurus TCAD. The proposed MOSFET achieves Enhancement-mode (E-mode) operation and better performance than the reported E-mode β-Ga₂O₃ transistors with CBLs. The DC characteristics present a higher on/off current ratio of 10⁸ than the reported β-Ga₂O₃ U-shaped MOSFETs, and a higher on-current density of 94 A/cm², a lower specific on-resistance of 26.5 m Ω⋅ cm², and a larger breakdown voltage of 483 V than the reported β-Ga₂O₃ current aperture vertical MOSFETs. The thermal characteristic study shows that the proposed device can work up to 500 ∘ C in E-mode operation with an on-current density of 35 A/cm² and on-resistance of 10⁴ m Ω .cm². The dynamic characteristics are explored, and excellent switching performance with a turn-on time of 29 ns and a turn-off time of 48 ns at room temperature is achieved. At 500 ∘ C, the turn-on time slightly increases to 38 ns due to the reduced electron mobility, and the turn-off time is still in the order of 40 ns because of the less discharge time of the lower on-state gate charge. The proposed MOSFET is examined in a boost converter application, and an efficiency of 89% and a voltage conversion ratio of 1.42 for a duty cycle of 40% are obtained. Our work shows the proposed β-Ga₂O₃ MOSFET has great potential as a high-speed switch in power electronics applications.