Wide-bandgap semiconductors like gallium oxide (β-Ga₂O₃) promise superior performance in high-power, high-temperature applications due to their large bandgap energy and high critical electric field. However, manufacturing challenges have limited their commercial deployment. A critical bottleneck is creating field termination structures—geometric features that redistribute electric fields to prevent premature device breakdown—without introducing plasma-induced damage that degrades electrical properties.
Researchers have successfully addressed this challenge using a plasma-free, gallium-assisted etching method within a low-pressure chemical vapor deposition system. The thermally activated process creates deep mesa structures while preserving device integrity, a substantial improvement over conventional plasma etching techniques that can cause crystalline defects and surface damage.
The fabricated Schottky barrier diodes demonstrated exceptional performance metrics. Forward conduction characteristics remained virtually unchanged compared to unetched reference devices, with turn-on voltage of 1.14V and specific on-resistance of only 3.72 mΩ·cm². The Schottky barrier height stabilized at approximately 1.15–1.23eV across measurement techniques, indicating excellent device uniformity.
Temperature testing from 25 to 250°C revealed stable thermionic emission behavior with manageable increases in on-resistance at elevated temperatures. Critically, reverse-bias breakdown voltage improved from 287V to 500V with the deep mesa structure, confirming effective electric-field redistribution. Leakage current remained low across the entire temperature range, and rectification ratios exceeded 10⁵ even at 250°C—a remarkable figure demonstrating minimal reverse conduction.
Simulation analysis using TCAD software validated the experimental results by showing significant suppression of electric-field crowding near device edges, the primary failure mechanism in high-voltage semiconductors. These results establish plasma-free etching as a reliable, reproducible field termination technique suitable for scaling β-Ga₂O₃ devices toward commercial power conversion applications. The approach eliminates a major manufacturing barrier, accelerating the practical deployment of gallium oxide in next-generation power electronics for grid infrastructure, electric vehicles, and renewable energy systems.
