体横光学声子双模性对纤锌矿Al_xGa_(1-x)N量子阱中光学声子的影响

Optical phonons in wurtzite Al_xGa_(1-x)N quantum wells affected by two-mode property of TO phonons

本文采用介电连续模型讨论纤锌矿Alx Ga1?x N的体横光学(TO)声子双模性对其量子阱中光学声子的影响.首先,给出Alx Ga1?x N中TO声子的频率的二次多项式拟合公式,在组分x=0和x=1时,使TO声子频率可回归至GaN和AlN情形.进而,分析Alx Ga1?x N含频介电函数随组分的变化.结果显示TO声子频率的单模或双模性将影响单个或两个共振频率下的含频介电函数;最后,以AlN/Alx Ga1?x N/AlN量子阱为例,计算界面和局域光学声子色散关系和声子静电势的影响.结果表明,纤锌矿Alx Ga1?x N的TO声子双模性在量子阱光学声子以及相关的理论计算中是不可忽略的.

In this paper, the dielectric continuum model is adopted to investigate the influence from two-mode property of transverse optical （TO） phonons on the optical phonons in wurtzite AlxGa1-xN quantum wells （QWs）. Firstly, a quadratic polynomial fitting has been proposed to approximate frequencies of TO phonons of AlxGa1-xN and to obtain the consistent values of GaN and A1N when x is 0 and 1 respectively. Furthermore, the dielectric functions of AlxGal^N varying with the A1 component have been analyzed. The results show that the one-mode or two-mode behavior of TO phonons will lead to one or two resonant frequencies of dielectric functions. Finally, as an example, the dispersion relations and electrostatic potential of interface and confined optical phonons in A1N/A1xGa1-xN/A1N QWs have been calculated. The results indicate that the two-mode property of TO phonons in A1GaN should not be ignored in the calculation of optical phonons in QWs and related theoretical works.