Electro-thermal Co-design of Vertical \b{eta}-Ga2O3 Schottky Diodes with High-permittivity BaTiO3 Field-plate for High-field and Thermal Management

TL;DR

This paper presents an electrothermal co-design approach for vertical ta-Ga2O3 Schottky diodes, utilizing high-permittivity BaTiO3 and AlN dielectrics to improve thermal management and high-field performance in high-power devices.

Contribution

It introduces a novel combination of BaTiO3 and AlN dielectrics in device structures to enhance heat dissipation and electric field management in ta-Ga2O3 Schottky diodes.

Findings

BaTiO3/AlN field-plate significantly reduces thermal hotspots.

AlN exhibits higher thermal boundary conductance than BaTiO3.

Vertical diodes with AlN achieve high breakdown field (~11 MV/cm).

Abstract

This work presents electrothermal co-design of vertical \b{eta}-Ga2O3 Schottky barrier diodes (SBDs) to enhance both heat dissipation and high field management in high-power applications. Here, we demonstrate device-level thermal management tailored for two vertical \b{eta}-Ga2O3 SBD structures that employed different edge termination techniques, such as field-plate and deep etch with sidewall field-plate, where the field-plate was formed with high-permittivity dielectric (BaTiO3). The localized thermal hot spots were detected at the Schottky contact edges near BaTiO3 dielectric based field-plate. However, a substantial reduction of the thermal hotspots was observed by forming the field-plate with BaTiO3 and thermally-conductive AlN insulator, where the AlN can effectively decrease Joule heating at interface and the high permittivity of BaTiO3 contributes to high field reduction. The deep etch and sidewall field-plate SBD structure further reduced accumulated heat and electric field near the critical anode edge by removing lateral depletion regions. We also analyzed thermal transport at dielectric/\b{eta}-Ga2O3 interfaces using Landauer approach that revealed significantly higher thermal boundary conductance (TBC) enabled by AlN compared to BaTiO3, attesting to the superior heat dissipation ability by BaTiO3/AlN field-plate than the BaTiO3-only configuration. Experimental investigation with vertical metal/AlN/\b{eta}-Ga2O3 diodes also extracted a high breakdown field (~11 MV/cm) of AlN, significantly exceeding the material breakdown field of \b{eta}-Ga2O3. This indicates that AlN can be an excellent choice for field-plate dielectric in vertical \b{eta}-Ga2O3 SBDs to provide both enhanced high field sustainability and improved heat dissipation in high-power applications.