Wide bandgap semiconductors for ultra high voltage devices. Design and characterization aspects

The development of high voltage devices is a great challenge. At least, railway and smart grids are examples of applications requiring high voltage devices. SiC power devices and technology seem to be mature enough to give a short term solution. Indeed, silicon carbide devices appear to be the semiconductor of choice for high voltage (> 6.5 kV) applications compared to Gallium Nitride. Diamond also is considered as a promising material for the next generation power devices. For high voltage devices, periphery protection is mandatory in order to reduce the well-known electric field crowding taking place at the junction edge. Some details are given about the different periphery technics (JTE, guard rings, MESA) applied to SiC and diamond devices, before combining some of them to reach higher and higher breakdown voltages. Finally, a new setup is under development in order to extract the ionization coefficients, compulsory to predict the breakdown voltage.