Strain effects on the polarized optical properties of InGaN with different In compositions
Author(s): Tao Ren-Chun, Yu Tong-Jun, Jia Chuan-Yu, Chen Zhi-Zhong, Qin Zhi-Xin), and Zhang Guo-Yi State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
Pages: 2603-2609
Year: 2009 Issue: 6
Journal: Chinese Physics B
Keyword: GaN; polarization degree; m-plane; relative oscillator strength;
Abstract: Strain effects on the polarized optical properties of c-plane and m-plane InxGa1-xN 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·p perturbation theory. For c-plane InxGa1-xN, it was found that the ROS of |X and |Y -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 |Z -like state decreased in the second band. For m-plane InxGa1-xN under compressive strain, the top three VBs were dominated by |X,|Z, and |Y -like states, respectively, which led to nearly linearly-polarized light emissions. For the top VB, ROS difference between |X and |Z -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.
Pages: 2603-2609
Year: 2009 Issue: 6
Journal: Chinese Physics B
Keyword: GaN; polarization degree; m-plane; relative oscillator strength;
Abstract: Strain effects on the polarized optical properties of c-plane and m-plane InxGa1-xN 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·p perturbation theory. For c-plane InxGa1-xN, it was found that the ROS of |X and |Y -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 |Z -like state decreased in the second band. For m-plane InxGa1-xN under compressive strain, the top three VBs were dominated by |X,|Z, and |Y -like states, respectively, which led to nearly linearly-polarized light emissions. For the top VB, ROS difference between |X and |Z -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.
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