Blueshift in MgxZn1-xO alloys: nature of bandgap bowing

Abstract

A Mg composition-dependent blueshift has been studied in MgxZn1−xO alloys deposited on 6H-SiC(0001) substrates. The localized exciton energy in MgxZn1−xO alloys for x ∼ 0.3 was blueshifted in the range 212–248 meV. The large negative bowing parameter was estimated in MgxZn1−xO alloys to be 4.72±0.84 eV. This large bandgap bowing emphasizes the Stokes shift, which has been attributed to the existence of spontaneous polarization effects due to the polar growth of MgxZn1−xO/SiC heterostructure and local compositional inhomogeneity.