【摘要】 本文先比较了几种常用方法(修正的无规元素等位移模型、虚晶近似和简化相干势近似等)对纤锌矿三元混晶体声子频率的拟合结果,再选用与实验数据接近的拟合方法,结合介电连续和单轴晶体模型导出含纤锌矿三元混晶InxGa1-xN和AlxGa1-xN单量子阱各类光学声子模的色散关系,进一步分析了声子模随组分的变化.结果表明,修正的无规元素等位移模型对单模性纤锌矿三元混晶体声子频率的拟合更接近实验数据.由于声子色散的各向异性,量子阱各类光学声子模随组分而发生变化,声子的局域模、界面模、半空间模以及传播模存在于特定组分和频率范围内,且同种声子模色散关系的形态也随组分而改变.更多还原

【Abstract】 Firstly,some results about the frequencies of phonons in wurtzite ternary mixed crystals(TMCs) fitted by several methods(modified random-element-isodiplacement model(MREI),virtual crystal approximation,and simplified coherent potential approximation,etc.) are compared.Then,combined with the continuous dielectric model and uniaxial crystal model,a fitting method available to experimental data is adopted to derive the dispersion relations of different kinds of optical phonon modes in TMC InxGa1-x N and AlxGa1-x N quantum wells.Furthermore,the variation of phonon modes dependent on the composition is analyzed.The results show that the fitting by the MREI for phonon frequencies of wurtzite TMCs with one-mode property agrees better with the experimental data.It can be also found that the optical phonon modes in quantum wells vary with the composition.The phonon modes,such as localized modes,interface modes,half-space modes,and propagating modes,exist in certain composition regions and frequency regions due to the anisotropy of phonon dispersion of wurtzite nitrides.Moreover,the shape of the same kind of phonon modes also varies with the composition.更多还原