BAND DISCONTINUITIES IN ZINCBLENDE AND WURTZITE ALN SIC HETEROSTRUCTURES/

The AlN/SIC band discontinuities in zinc-blende (110), (111), and wurt zite (0001) heterostructures were examined using the nb initio pseudop otential approach. At the nonpolar AlN/SiC(110) junction, we find a va lence-band offset of 1.7 eV. At the polar heterojunctions the band ali gnment depends on the interface composition, and valence-band offsets as high as 2.5 eV are obtained for neutral interfaces with an Al/Si mi xed plane and as low as 1.3 eV with a N/C mixed plane. Atomic relaxati on plays a major role in determining the offset. The structural change from cubic (111) to hexagonal (0001) heterojunctions affects predomin antly the conduction-band offset, and has only a minor influence on th e valence discontinuity.