Park Seoung-Hwan, Mishra Dhaneshwar, Eugene Pak Y, Kang K, Park Chang Yong, Yoo Seung-Hyun, Cho Yong-Hee, Shim Mun-Bo, Kim Sungjin
Opt Express. 2014 Jun 16;22(12):14850-8. doi: 10.1364/OE.22.014850.
Partial strain relaxation effects on polarization ratio of semipolar (112̄2) InxGa1−xN/GaN quantum well (QW) structures grown on relaxed InGaN buffers were investigated using the multiband effective-mass theory. The absolute value of the polarization ratio gradually decreases with increasing In composition in InGaN buffer layer when the strain relaxation ratio (ε0y′y′−εy′y′)/ε0y′y′ along y′-axis is assumed to be linearly proportional to the difference of lattice constants between the well and the buffer layer. Also, it changes its sign for the QW structure grown on InGaN buffer layer with a relatively larger In composition (x > 0.07). These results are in good agreement with the experiment. This can be explained by the fact that, with increasing In composition in the InGaN subsrate, the spontaneous emission rate for the y′-polarization gradually increases while that for x′-polarization decreases due to the decrease in a matrix element at the band-edge (k‖ = 0).
利用多带有效质量理论研究了生长在弛豫InGaN缓冲层上的半极性（112̄2）InxGa1−xN/GaN量子阱（QW）结构的部分应变弛豫对极化率的影响。当沿y′轴的应变弛豫率(ε0y′y′−εy′y′)/ε0y′y′被假定与阱层和缓冲层之间的晶格常数差成线性比例时，极化率的绝对值随着InGaN缓冲层中In组分的增加而逐渐减小。此外，对于生长在In组分相对较大（x > 0.07）的InGaN缓冲层上的量子阱结构，其符号会发生变化。这些结果与实验结果吻合良好。这可以通过以下事实来解释：随着InGaN衬底中In组分的增加，由于带边处（k‖ = 0）矩阵元的减小，y′极化的自发发射率逐渐增加，而x′极化的自发发射率则降低。
