Device breakdown and dynamic effects in GaN power switching devices: Dependencies on material properties and device design

摘要

High voltage GaN based transistors already showed promising device properties which makes them very attractive for future highly efficient power switching application. To further optimize device switching performance at high bias voltages the dependency of device breakdown and dynamic effects on device layer epitaxy and processing has to be analyzed. This paper discusses the dependencies of breakdown events, predominantly vertical breakdown between the device on the chip front side and the conductive n-type SiC or Si substrate on various technological parameters. They comprise high voltage buffer design and material quality, SiC substrate conductivity as well as metal contact technology of GaN HEMT devices. Furthermore a correlation between many of those parameters and dynamic switching properties has been determined. Physical mechanisms are then proposed to explain the basic inter-dependencies.