GaN结构相变、电子结构和光学性质

Structural Phase Transition,Electronic Structures and Optical Properties of GaN

运用第一性原理平面波赝势和广义梯度近似方法,对纤锌矿结构和氯化钠结构GaN的状态方程及其在高压下的相变进行计算研究,分析相变点附近的电子态密度、能带结构和光学性质的变化机制.通过状态方程和焓相等原理得到GaN从纤锌矿到氯化钠结构的相变压强分别为43.9Gpa和46.0Gpa;在相变的过程中,GaN由典型的直接带隙半导体转变为间接带隙半导体材料;氯化钠结构GaN相比于纤锌矿结构,介电函数主峰值增强,本征吸收边明显往高能方向移动,氯化钠结构GaN在低能区域的光学性质差于纤锌矿结构.

Equation of state and phase transformation under high pressure of two phases GaN have been calculated by means of plane wave pseudo-potential method with generalized gradient approximation.The electronic density of states,band structure and optical properties of change mechanism have been discussed near the point of phase transformation.the transition pressure of wurtzite and rock salt structure GaN is 43.9 Gpa and 46.0 Gpa by means of the equation of state and enthalpy equal principle respectively;The typical direct bandgap semiconductor of GaN became indirect bandgap semiconductor material on the structural phase transition process.Compared rock salt structure GaN with wurtzite,the main peak of the dielectric constant increases,the intrinsic absorption edge shift to high energy apparently.The optical properties of rock salt structure GaN is worse than wurtzite structure in the low energy region.