Abstract Strain effects on the polarized optical properties of $c$-plane and $m$-plane In$_x$Ga$_{1 - x}$N were discussed for different In compositions ($x=0$, 0.05, 0.10, 0.15) by analyzing the relative oscillator strength (ROS) and energy level splitting of the three transitions related to the top three valence bands (VBs). The ROS was calculated by applying the effective-mass Hamiltonian based on k$ \cdot$p perturbation theory. For $c$-plane In$_x$Ga$_{1-x}$N, it was found that the ROS of $\left| X \right\rangle$ and $\left| Y \right\rangle$-like states were superposed with each other. Especially, under compressive strain, they dominated in the top VB whose energy level also went up with strain, while the ROS of the $\left| Z \right\rangle$-like state decreased in the second band. For $m$-plane In$_x$Ga$_{1-x}$N under compressive strain, the top three VBs were dominated by $\left| X \right\rangle$, $\left| Z \right\rangle$, and $\left| Y \right\rangle$-like states, respectively, which led to nearly linearly-polarized light emissions. For the top VB, ROS difference between $\left| X \right\rangle$ and $\left| Z \right\rangle$-like states became larger with compressive strain. It was also found that such tendencies were more evident in layers with higher In compositions. As a result, there would be more TE modes in total emissions from both $c$-plane and $m$-plane InGaN with compressive strain and In content, leading to a larger polarization degree. Experimental results of luminescence from InGaN/GaN quantum wells (QWs) showed good coincidence with our calculations.
Received: 11 November 2008
Revised: 22 December 2008
Accepted manuscript online:
Fund: Project supported by the National
Natural Science Foundation of China (Grant Nos 60676032, 60577030
and 60776042) and National Key Basic Research
Special Foundation of China (Grant No TG 2007CB307004).
Cite this article:
Tao Ren-Chun(陶仁春), Yu Tong-Jun(于彤军), Jia Chuan-Yu(贾传宇), Chen Zhi-Zhong(陈志忠), Qin Zhi-Xin (秦志新), and Zhang Guo-Yi(张国义) Strain effects on the polarized optical properties of InGaN with different In compositions 2009 Chin. Phys. B 18 2603
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