  SiC is set to enable a new era in power electronics impacting a wide range of
energy technologies, from electric vehicles to renewable energy. Its physical
characteristics outperform silicon in many aspects, including band gap,
breakdown field, and thermal conductivity. The main challenge for further
development of SiC-based power semiconductor devices is the quality of the
interface between SiC and its native dielectric SiO$_2$. High temperature
nitridation processes can improve the interface quality and ultimately the
device performance immensely, but the underlying chemical processes are still
poorly understood. Here, we present an energy-dependent hard X-ray
photoelectron spectroscopy (HAXPES) study probing non-destructively SiC and
SiO$_2$ and their interface in device stacks treated in varying atmospheres. We
successfully combine laboratory- and synchrotron-based HAXPES to provide unique
insights into the chemistry of interface defects and their passivation through
nitridation processes.
