Seminar: Advancing WBG and UWBG Semiconductors for Power Electronics and More

Join us for a seminar with Dr. Hongping Zhao, professor in the Department of Electrical and Computer Engineering at Ohio State University.

Abstract: Wide bandgap gallium nitride (GaN), with an intrinsic breakdown field of 3.5 MV/cm and a phonon-limited electron mobility exceeding 2000 cm²/Vs, offers a Baliga figure of merit superior to SiC and Si. This enables substantial reductions in conduction and switching losses in power electronics. While extensive research has focused on lateral power switching transistors, vertical GaN device configurations enable scalability in both current and voltage for high power applications. This talk will discuss the development of laser-assisted metalorganic chemical vapor deposition (MOCVD) for GaN-on-GaN, targeting high-performance vertical PN diodes. Recent advances have demonstrated a record-breaking breakdown voltage exceeding 11 kV for vertical GaN diodes.

Additionally, MOCVD epitaxy of several other WBG and UWBG semiconductors will be discussed. Derived conceptually from III-nitrides, II-IV-nitrides replace two group III atoms with a pair of group II and group IV atoms, opening new possibilities for band structure and device engineering. This talk will highlight MOCVD developments of several II-IV-N2 (ZnGeN2, ZnSnN2, MgGeN2 and MgSiN2) and their applications in optoelectronics and electronics.

Moreover, ultra-wide bandgap gallium oxide (Ga₂O₃), with a bandgap energy of 4.8 eV and a predicted critical field strength of 8 MV/cm, emerges as a promising material for power electronics. Significant progress has been made in Ga₂O₃ substrate development, thin film epitaxy, defect and doping control, and device demonstrations. I will discuss recent MOCVD advancements at OSU, focusing on doping/impurities, charge transport, alloy formation, phase stabilization, and heterostructures.

Biography: Hongping Zhao is a professor in the Department of Electrical and Computer Engineering and the Department of Materials Science and Engineering at The Ohio State University (Columbus, Ohio). Prof. Zhao's research expertise lies in wide bandgap and ultra-wide bandgap semiconductor materials and devices. Her current work focuses on the material synthesis and device physics of III-nitrides, II-IV-nitrides, gallium oxide, among others. She is currently an Associate Editor for Applied Physics Letters and the Journal of Crystal Growth.