Non-polar m-plane GaN film and polarized InGaN/GaN LED grown on LiAlO 2 (001) substrates

Abstract

The non-polar m-plane GaN film and polarized InGaN/GaN light-emitting diode (LED) grown by metal-organic chemical vapor deposition (MOCVD) on LiAlO 2 (100) substrates were investigated. Firstly, the simulation of excitonic transition energies and polarization effects on band structure of non-polar plane GaN was studied using the k· p Hamiltonian approach. Due to small lattice mismatch between GaN and LiAlO 2 substrate, X-ray diffraction (XRD) revealed that the obtained m-plane GaN film has only [11-00] orientation with single-crystalline quality. In addition, anisotropic crystallographic properties and strain were found, which originates from the broken hexagonal symmetry. The anisotropic strain further separates the energy levels of top valence band at Γ point. The energy splitting as 37meV as well as in-plane polarization anisotropy for transitions are found by the polarized photoluminescence spectra at room temperature, which is consistent with our simulation. The fabricated InGaN/GaN LED on LiAlO 2 (100) emits green polarized light at room temperature. And the polarization degree of the emission reaches up to 60% at the wavelength of 520nm.