Development of experimental techniques for the analysis of instabilities in GaN devices

The thesis is composed of a brief portrayal of the experimental results obtained by analysis of wide bandgap material devices, specifically Gallium Nitride (GaN) ones. In addition to that, an innovative measurement technique to measure the instabilities of certain device parameters in different stress conditions is explored. The devices are tested in the Advanced Characterization and Modelling of Electronics [ACME] lab in the Department of Information Engineering [DEI] of the University of Padua, whereas the test structures are manufactured by Ferdinand-Braun-Institut [FBH],Berlin. In the first part of the thesis, p-n diodes are analyzed by performing IV and temperature-dependent IV to investigate the leakage current and on-resistancce of the devices. Further, the breakdown mechanism of the devices are investigated by performing breakdown tests and temperature-dependent breakdown tests to study the avalanche mechanism. In the second part, GaN vertical trench MOSFETs are analyzed by performing DC characterization tests like IDVG, IDVD, IGVG, and IGVD tests investigating device performance, leakage, and instabilities in threshold voltage. In the final part of the thesis, a new approach to measure threshold voltage instabilities is explored and a measurement setup is devised that can measure threshold voltage with a measurement time as low as 1us and can apply pulsed gate stress up to 25 V. Tests are performed on different devices like packaged Si power MOSFETs, SiC, Gan-Hemts, and Gan vertical trench MOSFETs [by FBH] to analyze the transient in threshold voltage hence gaining a better understanding of the charge trappings in the devices.