Semiconductor device developments are typically guided by simulations – what is the best epitaxial design, or how should field plates or edge terminations be designed. To assess how a particular device reflects what has been designed, comparing IV curves measured and simulated is typical, but for example different implantation or doping levels can lead to the same too low breakdown voltage, and there is then little guidance for example how to mitigate such a problem to optimize/enhance breakdown voltage. We illustrate the latest capability of a technique we developed, based on electricfield- induced optical second-harmonic generation (EFISHG), on vertical GaN-on-GaN pn junction examples, to directly access with submicron spatial resolution electric strength in a device, to aid improving device design and their implementation, and reducing product development cycles.
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