Optimization of Step-Etched Junction Termination Extensions for Vertical GaN Devices

• Published in: IEEE transactions on electron devices Vol. 71; no. 3; pp. 1541 - 1545
• Main Authors: Binder, Andrew T., Steinfeldt, Jeffrey, Allerman, Andrew A., Rummel, Brian D., Glaser, Caleb, Yates, Luke, Kaplar, Robert J.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-03-2024; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Breakdown; Doping; edge termination; Electric breakdown; Electric fields; Gallium nitride; Gallium nitrides; Image edge detection; junction termination extension (JTE); Junctions; Passivation; power devices; Semiconductor diodes; Surface charge; vertical gallium nitride (GaN)
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2023.3344057

This work provides the first demonstration of a multipoint fit from theory to experiment for step-etched junction terminations on vertical gallium nitride (GaN) devices. Viable edge termination methods in GaN are limited due to challenges with selective-area doping. We report on a study that determines the optimal charge in the junction termination extension (JTE) of a GaN-based p-n diode to aid in the design of multizone JTEs. Experimental results show a step-thickness offset compared to theoretical prediction, which is attributed to plasma-induced etch damage, as well as variation in passivation-related charge, surface charge, and doping profile variations. Results are supported by electroluminescence imaging, which confirms the match from theory to experiment.