高压下GaN的电子结构及光学性质的理论研究

Theoretical Study of the Electronic Structure and Optical Properties of GaN under High Pressure

基于密度泛函理论,深入讨论了GaN(闪锌矿(B3)和氯化钠(B1))的晶体结构、相变压强和弹性性质.用等焓原理,获得B3→B1的相变压强为44.6 GPa,与相关的理论结果吻合较好.随着压强的增加,GaN的静态介电常数ε1(0)逐渐减小.介电函数的实部ε1(ω)和虚部ε2(ω)的第一个峰都向入射光子的高能方向移动,而且强度逐渐减弱.此外,压强对吸收光谱和折射率也有重要的影响.

The crystal structures and phase transition of GaN have been studied out based on density functional theory. Using the enthalpy-pressure data, we have observed the B3 to B1 structural phase transition pressure at 44.6 GPa. With increasing pressure, the static dielectric constants reduce and the first strong peak in ε1 （w） and ε2 （w） shifts towards higher incident photon energy, and the intensity gradually weakens. In addition, the pressure also has an important impact on the absorption spectrum and refractive index of GaN.