arXiv subjects

Emerson J. Hollar

Publications and source records attributed to Emerson J. Hollar.

3 recordsLinked to original sources

arXiv2026

Kilovolt-class Vertical (011) \b{eta}-Ga2O3 Schottky Diodes for High Voltage and High Temperature Applications

We report kilovolt-class vertical (011) \b{eta}-Ga2O3 Schottky diodes utilizing high-permittivity dielectric TiO2/Al2O3 field-plate for high voltage and high temperature applications. A systematic study was performed with Pt/(011) \b{eta}-Ga2O3 Schottky barrier diodes (SBDs) with varied diameters from 100 μm to 300 μm, for both with and without field-plate, that revealed excellent consistency of reverse blocking performance regardless of diode area. The field-plate SBDs achieved superior breakdown voltages (3.90 - 4.16 kV) compared to the diodes without field-plate (3.06 - 3.16 kV) owing to effective edge termination. Furthermore, we explored high-temperature performance of the field-plate (011) \b{eta}-Ga2O3 diodes that revealed excellent forward conduction properties and high rectification ratio (~10^9) throughout the temperature range (25 - 150 C). At reverse bias, the field-plate diodes also exhibited kV-range breakdown voltage with no evident increase in leakage current up to the explored elevated temperature of 150 C. The low area-dependence of breakdown voltage, excellent forward transport properties, and minimal reverse leakage at both high-voltage and elevated temperature demonstrate the exciting potential of (011) \b{eta}-Ga2O3 SBDs in high-temperature power switches. Thus, our work demonstrates the strategy of advancing the performance of vertical \b{eta}-Ga2O3 SBDs by utilizing the advantageous (011) \b{eta}-Ga2O3 epilayers with low background doping, reduced killer dislocation effects, and effective field management for high-voltage and high-temperature applications.

cond-mat.mtrl-sci↗

arXiv2025

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

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.

cond-mat.mtrl-sci↗

arXiv2025

Over 3 kV and Ultra-Low leakage Vertical (011) \b{eta}-Ga2O3 Power Diodes with Engineered Schottky Contact and High-permittivity Dielectric Field Plate

We report over 3 kV breakdown voltage and ultra-low leakage (011) \b{eta}-Ga2O3 power devices utilizing Schottky barrier engineering and high-permittivity (\k{appa}) dielectric (ZrO2) field plate. The (011) orientation of \b{eta}-Ga2O3 enabled low background doping and thick drift layers which are promising to support kV-class vertical \b{eta}-Ga2O3 power switches. The Schottky barrier engineering was performed with a composite Pt cap/PtOx/Pt (1.5 nm) anode contact to take advantage of the enhanced reverse blocking capabilities enabled by PtOx while allowing low turn-on voltage by the interfacing thin Pt layer. We also performed a systematic study using a co-processed Pt/(011) \b{eta}-Ga2O3 Schottky barrier diodes (SBDs) on the same wafer. The bare SBDs revealed a breakdown voltage of ~1.5 kV, while the field-plate Pt/(011) \b{eta}-Ga2O3 SBDs achieved an increased breakdown voltage of 2.75 kV owing to the edge field management. Further enhancement of the breakdown voltage was achieved by tunneling leakage management using composite Pt cap/PtOx/Pt (1.5 nm) Schottky contacts that ultimately enabled breakdown voltage of 3.7 kV for the field-plate diodes. Remarkably, the Pt cap/PtOx/Pt (1.5 nm) Schottky contacts maintained similar turn-on voltage as the Pt/(011) \b{eta}-Ga2O3 SBDs. The combination of efficient tunneling leakage management by composite Pt cap/PtOx/Pt (1.5 nm) contacts with similar turn-on voltage, edge field reduction by high-\k{appa} dielectric ZrO2 field plate, as well as the advantageous material properties offered by (011) \b{eta}-Ga2O3 demonstrate a promising strategy for developing ultra-low leakage and multi-kV class vertical (011) \b{eta}-Ga2O3 power devices.

eess.SY↗