Vertical Devices In Bulk GaN Drive Diode Performance To Near - Theoretical L imits
by sik C. Kizilyalli, Andrew Edwards, David Bour, Hemal Shah, Hui Nie, and Don Disney, Avogy, San Jose, Calif., How2Power Today, Mar 15 2013
Focus:
A major reason for developing GaN power devices is that the fundamental material-based figure-of-merit (FOM) of gallium nitride (GaN) is at least five times better than silicon carbide (SiC) and nearly 1000 times that of Si. In this article, the authors explain how their company is taking full advantage of the material properties of GaN by fabricating vertical diodes on low-defect-density bulk GaN substrates. The 600-V to 1700-V rated devices described here demonstrate performance near theoretical limits as predicted by GaN material properties. In addition, measurements reveal robust avalanche breakdown. After briefly noting the implications of GaN device properties on device performance with comparisons to silicon and SiC, the article describes the company’s approach to designing vertical GaN Schottky-barrier diodes and pn diodes, presents I-V charactieristics for these devices; compares FOMs for Avogy’s vertical GaN diodes with vertical SiC, lateral GaN and other vertical GaN diodes; and presents data on avalanche capability. Then, the impact of Avogy’s diodes on applications is discussed. In a hard-switched boost circuit, the pn diodes reduce overshoot and ringing versus ultra-fast silicon rectifiers. In a half-bridge circuit, the pn diodes improve efficiency versus high-speed silicon diodes. Some data is given on high-temperature-reverse-bias testing of Avogy’s 1200-V pn diodes.
What you’ll learn:
- How to understand the material benefits of GaN versus silicon and silicon carbide in the development of power devices
- How to understand the benefits of Avogy’s lateral device design for Schottky and pn GaN diodes
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