Cryogenic operation of 4H-SiC Schottky rectifiers

We report the performance of commercial 4H-SiC Schottky rectifiers at cryogenic temperatures for the first time. The Infineon rectifiers rated 300V and 600V have been tested for both forward conduction and reverse blocking at temperatures down to 77K. The barrier height decreased with temperature while the ideality factor is greater than unity implying that diffusion also plays a role in current conduction at cryogenic temperatures. A two barrier height Schottky effect has been noticed at lower temperatures indicating barrier inhomogeneities in the Schottky contacts. At lower temperatures, tunneling current played a major role in the transport process.