Excitation light intensity dependence of 2.2 eV yellow photoluminescence of n-type GaN

The room-temperature 2.2 eV photoluminescence intensity of n-type GaN grown by metal-organic vapor phase epitaxy was found at lower excitation intensities to be proportional to excitation intensity and at higher excitation intensities to be proportional to the 1/3 power of the excitation intensity. That of undoped bulk GaN grown by hydride vapor phase epitaxy, however, was proportional to the excitation intensity throughout the excitation region. The luminescence is thought from the intensity proportional to the 1/3 power of the excitation intensity not to be the result of a conventional process. The observed proportionality is well explained by exciton–exciton annihilation in one-dimensional structures.