CHEMICAL TREND OF BAND OFFSETS AT WURTZITE ZINCBLENDE HETEROCRYSTALLINE SEMICONDUCTOR INTERFACES

The band structures of various semiconductors in both wurtzite (WZ) and zinc-blende (ZB) structures are calculated using the first-principles pseudopotential method within the local-density approximation, and then the band offsets at (111) WZ/ZB interfaces are evaluated for the band-edge states around fundamental gaps. We found that the band offsets are larger for ''zone-boundary states'' having large wave numbers perpendicular to [111] than for ''zone-center states'' having small wave numbers perpendicular to [111]. These phenomena occur because the former offsets are caused by the phase matching of a wave function through the first-nearest-neighboring site, whereas the latter are caused by the difference between the position of the third-nearest-neighboring site in the WZ and ZB structures. In addition, we show that the band offset increases with decreasing ionicity of the constituent semiconductor material, i.e., the magnitude of the band offset is determined by the competition between ionicity and covalency.