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

Abstract

The strain effects of the Zn1−xMgxO substrate on the bands structure of wurtzite Nb-doped ZnO bulk materials have been investigated using first-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/Zn1−xMgxO. Splitting energies between HHB (Heavy Hole Band) and LHB (Light Hole Band), HHB and CSB (Crystal Splitting Band) in Zn0.9167Nb0.0833O/Zn1−xMgxO almost remain unchanged with increasing substrate stress, while decrease slightly in Zn0.875Nb0.125O/Zn1−xMgxO. In addition, detailed analysis of the strain effects on the effective masses of electron and hole in Nb-doped ZnO/Zn1−xMgxO is also given.