Electro-thermal co-design of vertical β-Ga2O3 Schottky diodes with high-permittivity BaTiO3 field-plate for high-field and thermal management

This work presents electrothermal co-design of vertical β-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 β-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 the BaTiO3 dielectric based field-plate. However, a substantial reduction of the thermal hotspots was observed by forming the field-plate with BaTiO3 and a thermally conductive AlN insulator, where the AlN can effectively decrease Joule heating at the 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/β-Ga2O3 interfaces using the Landauer approach, which revealed significantly higher thermal boundary conductance (TBC) enabled by AlN compared to BaTiO3, attesting to the superior heat dissipation ability of the BaTiO3/AlN field-plate compared to the BaTiO3-only configuration. Experimental investigation with vertical metal/AlN/β-Ga2O3 diodes also extracted a high breakdown field (∼11 MV/cm) of AlN, significantly exceeding the material breakdown field of β-Ga2O3. This indicates that AlN can be an excellent choice for field-plate dielectric in vertical β-Ga2O3 SBDs to provide both enhanced high field sustainability and improved heat dissipation in high-power applications.