Silicon carbide (SiC) is a wide-bandgap semiconductor considered to be one of the major enabling materials for advanced high power and high temperature electronics applications. In addition to its wide bandgap, SiC also has a high critical electric field strength and a high saturation drift velocity, can be doped both n- and p-type with relative ease, has SiO2 as native oxide. Up to six inch wafers with thickness and doping variations below 10%, are now commercially available. With recent improvements in crystal growth and material processing, SiC-based electronics is now superior for power conversion than state-of-the-art silicon-based electronics, especially for high-temperature, high-voltage and high-frequency applications.
Fig. 1: (a) Transconductance for a lateral SiC MOSFET as shown in the inset, VSD = 0.5V. (b) HR-TEM z-contrast image of the SiO2 /SiC Interface. (c) Band structure of 4H-SiC, buried under a 2 nm layer of SiO2.
At the Laboratory for Micro and Nanotechnology (LMN), and in collaboration with the Advanced Power Semiconductor Laboratory (APS) at ETH Zürich, we are involved in the development and optimization of all the necessary steps for the fabrication of MOSFET transistors. This allows us to study and improve the different processes at the material level (using morphological and chemical analysis at the nano scale based on the unique, mostly synchrotron based techniques available at PSI, such as X-ray photoemission spectroscopy XPS, atomic force microscopy AFM, Trasmission and Scanning Electron Microscopies, TEM and SEM) and on the electrical level, extracting properties such as channel mobility and interface defectivity as function of the fabrication processes.
A significant part of our research is embedded in the “Swiss Transformer” project, funded by the Swiss National Science Foundation under the NRP 70 program.
In parallel, we are also investigating the tolerance of this wideband gap material to high fluence X-ray beams. Aim of this Research is to assess its potential for next generation X-ray beam position monitors and detectors to be used in Synchrotrons and XFELs.