Direct observation of conduction-band structure of 4H- and 6H-SiC using ballistic electron emission microscopy

We performed ballistic electron emission microscopy (BEEM) measurements on Pt and Pd/4H- and 6H-SiC Schottky contacts, obtained Schottky barrier heights, and observed qualitatively different behavior of the BEEM spectra for 4H- and 6H-SiC. In particular, in 4H-SiC we observed an additional minimum similar to 0.14 eV above the lowest conduction-band minimum. We calculated the electronic band structure for both polytypes and found it in good quantitative agreement with our BEEM observations as well as good qualitative agreement with previous SiC band-structure calculations. [S0163-1829(98)03307-4].