ZnO epitaxy on SiC( [formula omitted]) substrate: Comparison with ZnO/SiC(0 0 0 1) heterostructure

Abstract

ZnO thin layers deposited on 6H–SiC substrates showed six-fold crystal symmetry with an epitaxial relationship of (0 0 0 2) ZnO||(0 0 0 6) SiC and [ 1 1 2 ¯ 0 ] ZnO||[ 1 1 2 ¯ 0 ] SiC. Despite the different 6H–SiC substrate surface orientations for the ZnO epitaxy, the orientation relationship of ZnO/6H–SiC heterostructures is identical, as confirmed by X-ray diffraction studies. In these ZnO/6H–SiC(0 0 0 1) and ZnO/6H–SiC( 0 0 0 1 ¯ ) heterostructures, the valence band offsets are measured to be 1.12 eV and 1.09 eV, leading to the conduction band offset values of 0.75 eV and 0.72 eV, respectively. These slightly different band-offset values in ZnO/6H–SiC heterojunctions are attributed to the variation of valence band maximums and the different interface charge compensation mechanisms.