Impact of metal diffusion, lattice distortions, native defects, and ambient on dielectric breakdown in Ni–Ga₂O₃ Schottky diodes

Journal Article · 24 October 2024 · APL Materials

DOI: https://doi.org/10.1063/5.0228825 · OSTI ID:2507411

Ramdin, Daram N.  ^[1]; Huang, Hsien-Lien  ^[1]; Chae, Christopher  ^[1]; Dhara, Sushovan ^[1]; Rajan, Siddharth ^[1]; Hwang, Jinwoo  ^[1]; Brillson, Leonard J.  ^[1]

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1. The Ohio State University, Columbus, OH (United States)

Ga₂O₃ unipolar devices are of high interest due to their ~8 MV/cm predicted breakdown fields, which have not yet been achieved due to premature device failure. Pre- and post-failure defect analysis of Ni–Ga₂O₃ Schottky diodes in ultrahigh vacuum (UHV) and air were performed using depth-resolved cathodoluminescence, high angle annular dark field scanning transmission electron microscopy, and energy dispersive x-ray analysis to understand the physical mechanisms that precede premature breakdown. The breakdown voltage in UHV was dramatically reduced by nearly 40% compared with the breakdown in air. This reduction in the breakdown voltage correlated with post-breakdown differences in Ni distribution, indicating that the coordination and bonding of Ni contribute strongly to electrical behavior in Ni–Ga₂O₃ Schottky diodes. Breakdown studies in UHV revealed that Ni diffuses away more from the metal–semiconductor interface than with air breakdown, where Ni localizes more near the interface, indicative of the preferential formation of a Ni oxide under O-poor conditions. These measurements also identified the formation of divacancy-interstitial complexes and their characteristic luminescence signature ~150 nm from the interface, the densities of which correlated with breakdown fields. These findings show that electric-field-induced degradation occurs via the rearrangement of native point defects, which act as an additional precursor to device failure. Macroscopically, they show the impact of both vacuum conditions and metal reactivity on Ga₂O₃ device fabrication.

• Research Organization: Georgia Institute of Technology, Atlanta, GA (United States)
• Sponsoring Organization: Air Force Office of Scientific Research (AFOSR); National Science Foundation (NSF); USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: NA0003921
• OSTI ID: 2507411
• Journal Information: APL Materials, Journal Name: APL Materials Journal Issue: 10 Vol. 12; ISSN 2166-532X
• Publisher: American Institute of Physics (AIP)Copyright Statement
• Country of Publication: United States
• Language: English