Afirst principles calculation is used to simulate the changes of the lattice constant

band gap

total energy and structure of MgZnO semiconductor alloys with the different MgO mole fractions.The calculated results show that the lattice constant diminishes and the crystal structure departures gradually from the wurtzite type as the MgO mole fraction increases.By comparison with the different positions of the Mg atom

it is suggested that the structure of Mg

x

Zn

1-x

Oalloy will change and the possibility of the phase transition will be higher than that of the phase separation as the MgO mole fraction increases.On the other hand

when the MgO mole fraction is increased

the band gap enlarges

which is mainly attributable to the shift of the top of the valence band away from the Fermi level.By construing the influence of all kinds of electronic states in Mg atom on the valence band

it shows that the contribution of Mg to the energy band near the top of the valence band takes turn from its p

d

s states.The density of the p states near the top of the valence band enhances prominently when the MgO mole fraction is increased.It indicates that the sp hybridization not only affects the structure of the crystal but also plays an important role for its electronic structures.