Localized luminescence centers of InGaN

Abstract

A study was carried out on the low-temperature photoluminescence (PL) and PL excitation measurements of hexagonal InxGa1−xN microcrystals, synthesized by the nitridation of the sulfide in the In concentration range, 2%<x<6%. The broad PL bands decomposed into the single-peak bands with the commonly observed peaks and some additive peaks. The peak energies of the single-peak bands were compared with those of the bands for InxGa1−xN epilayers in previous reported results and the transitions of the selected single-peak bands were assigned to the recombination of the exciton at localized levels due to alloy disorder. The large Stokes shifts and the absorption band within a gap confirmed the luminescence center states were localized. To explain the facts that the gap energy varied for the samples with the same In content and the emission peak energy did not relate to the band gap energies, we proposed that the localized states originate from the In clusters caused by the fluctuation of the In concentration. This type of localized center provides the microscopic structures of the localized states in InxGa1−xN epilayers.