Huge electron-hole exchange interaction in aluminum nitride

Abstract

Optical spectroscopy is performed for c-plane homoepitaxial aluminum nitride (AlN) films. The temperature dependence of the polarization-resolved photoluminescence spectra reveals the exciton fine structure. The experimental results demonstrate that the electron-hole exchange interaction energy (j) in AlN is j=6.8 meV, which is the largest value for typical III-V and II-VI compound semiconductors. We propose the effective interatomic distance as the criterion of the electron-hole exchange interaction energy, revealing a universal rule. This study should encourage potential applications of excitonic optoelectronic devices in nitride semiconductors similar to those using II-VI compound semiconductors.