First-principles theoretical study on band of strained wurtzite Nb-doped ZnO

Abstract

The strain effects of the Zn 1x Mg x O substrate on the bands structure of wurtzite Nb-doped ZnO bulk materials have been investigated using fi rst-principles calculations based on density functional theory. Firstly, the band gap increases gradually with increasing Nb contents in unstrained Nb-doped ZnO, which is consistent with the experimental results. Secondly, the band gap decreases with increasing substrate stress in Nb-doped ZnO/Zn 1x Mg x O. Splitting energies between HHB (Heavy Hole Band) and LHB (Light Hole Band), HHB and CSB (Crystal Splitting Band) in Zn 0.9167 Nb 0.0833 O/Zn 1x Mg x O almost remain unchanged with increasing substrate stress, while decrease slightly in Zn 0.875 Nb 0.125 O/Zn 1x Mg x O. In addition, detailed analysis of the strain effects on the effective masses of electron and hole in Nb-doped ZnO/Zn 1x Mg x O is also given.