Enhancing Reliability in Ga2O3, GaN, and SiC Wide-Bandgap Semiconductor Devices Through Structural Design Improvement and Radiation Effects Analysis

Abstract

Wide bandgap (WBG) semiconductor technologies such as gallium oxide (Ga2O3), gallium nitride (GaN), and silicon carbide (SiC) are transforming power electronics by enabling higher breakdown fields, faster switching, and improved efficiency compared to silicon. Each material has unique advantages and tradeoffs for specific applications. Ga2O3 has the widest bandgap, enabling high-voltage operation and compact devices, but suffers from poor thermal management. GaN, with high electron mobility and low switching losses, is ideal for high-frequency systems that require fast operation. SiC, with excellent thermal conductivity and a high breakdown field, is preferred for high-temperature, high-power applications. These considerations motivate the need to improve the performance and reliability of WBG devices across all material platforms, forming the foundation of this dissertation. Power devices remain vulnerable when operated in radiation environments such as space. High-energy ions and particles in cosmic and solar radiation can induce single-event effects (SEE, SELC, SEB), a radiation effect caused by an energetic particle striking the device. They can cause irreversible damage to the device, including permanent leakage increase and catastrophic failure. Therefore, it is essential to understand the underlying mechanisms causing damage to enhance device robustness under radiation. 2 In this dissertation, I experimentally investigated how structural optimization, epitaxial design, and termination engineering improve reliability and radiation hardness. For Ga2O3 and GaN, optimizing device structure through increased epitaxial thickness, improved edge termination, and better anode and passivation materials enhances electrical breakdown limit and radiation tolerance. Experimental results from high-voltage SiC devices advance the understanding of how epitaxial doping influences the voltages at which damage occurs. The dissertation also establishes relationships among ion range, linear energy transfer, and SEB thresholds, clarifying how these parameters interact with device design and epitaxial structure. The results reveal design dependencies governing radiation-induced degradation across WBG material systems and guide the development of high-reliability power devices for extreme environments, i.e., space and defense.