MgxZn1-xO结构性质

采用第一性原理计算模拟了不同组分的Mg_xZn_1-xO半导体混晶的晶格常数、总能、结构,以及禁带宽度的变化。计算结果显示,随着Mg组分的增加,晶格常数逐渐减小,晶体逐渐偏离纤锌矿结构。对各种不同的Mg原子排列情况进行比较认为,Mg_xZn_1-xO的结构随组分x的增大,发生从纤锌矿到岩盐矿的结构相变的可能性高于发生相分离。另一方面,禁带宽度随组分增大主要由价带顶的移动所致。进一步分析Mg原子各种电子态对价带的影响表明,Mg对价带顶附近能带的贡献依次来自p、d、s态电子。随着组分x的增加,p态电子在价带顶附近的密度明显提高,说明sp轨道杂化不但对晶体的几何结构产生影响,而且对其电子结构也起重要作用。

The Structure Properties of MgxZn1-xO

A first 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_xZn_ 1-xO alloy 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.