Performance and robustness characterisation of SiC power MOSFETs

Over the last few years, significant advancements in the SiC power MOSFET fabrication technology has led to their wide commercial availability from various manufacturers. As a result, they have now transitioned from being a research activity to becoming an industrial reality. SiC power MOSFET technology offers great benefits in the electrical energy conversion domain which have been widely discussed and partially demonstrated. Superior material properties of SiC and the consequent advantages are both later discussed here. For any new device technology to be widely implemented in power electronics applications, it’s crucial to thoroughly investigate and then validate for robustness, reliability and electrical parameter stability requirements set by the industry. This thesis focuses on device characterisation of state-of-the-art SiC power MOSFETs from different manufacturers during short circuit and avalanche breakdown operation modes under a wide range of operating conditions. The functional characterisation of packaged DUTs was thoroughly performed outside of the safe operating area up until failure test conditions to obtain absolute device limitations. For structural characterisation, Infrared thermography on bare die DUTs was also performed with an aim to observe hotspots and/or degradation of the structural features of the device. The experimental results are also complemented by 2D TCAD simulation results in order to get a further insight into the underlying physical mechanisms behind failure during such operation regimes. Moreover, the DUTs were also tested for body diode characterisation with an aim to observe degradation and instability of electrical device parameters which may adversely affect the performance of the overall system. Such investigations are really important and act as a feedback to device manufacturers for further technological improvements in order to overcome the highlighted issues with an aim to bring about advancements in device design to meet the ever-increasing demands of power electronics