First-principles study on crystal phase superlattice nanowires heterostructures

Abstract

We perform a first-principles density functional theory study on structural and electronic properties of a sery of crystal-phase heterostructure atomic-scale superlattice (SL) nanowires (NW) from GaN material, i.e. GaN wurtzite(WZ) /zincblende (ZB) material interface. The effects of surface/interface relaxation and surface stress which are absent in atomistic models are carefully taken into account. Structural properties, energy bands and electronic properties for a class of hexagonal wires with various period of SL structure and diameter size are discussed. Pseudo hydrogen atoms, i.e. hydrogen with partial charges, are used to passivate the dangling surface bonds, which remove the localized in-gap surface states and suppress the surface reconstructions. With this passivation procedure the band structure show the type II for all wires. While the electrical aspects of these SL nanowires are explored through density functional theory, their subsequent band structures are used to determine the thermoelectric properties via the Boltzmann transport theory. Finally, the thermoelectric propertys dependence on temperature is unveiled.