Characteristics of Polarization Emission in a-plane GaN-based Multiple Quantum Wells Structures

Abstract

In this paper, we investigated polarized light emission properties on a series of $a$ -plane GaN/AlGaN multiple quantum wells grown on $r$-plane sapphire substrates with various well widths by using the polarization-dependent photoluminescence measurement. To clarify reasons of polarization properties in light emission, we applied the 6 $\,\times\,$6 $k\cdot p$ model to simulate the $E{\hbox{--}}K$ dispersion relationship and wave functions to obtain optical transitions of different polarized emissions. According to our results, the sub-bands of $\vert {\rm Y}>$-like states are raised toward the top of the valence sub-band level with increasing the well width. And the optical matrix element of $y$-polarized light emission will dominate the optical transition, leading to the increase of degree of polarization in the thicker well.