Abstract
The high mobility of electrons in cubic SiC is shown to be due to selection rules which severely restrict intervalley scattering. Only longitudinal acoustic (LA) phonons are permitted, and these have such a high energy (79.4 meV) that they are unimportant at room temperature. On the other hand, electron mobility in the common SiC polytypes, 6H and 15R, is limited by intervalley scattering.