Analysis of the local indium composition in ultrathin InGaN layers

Experimental photoluminescence (PL) spectra and structural properties of the ultrathin InGaN insertions in an AlGaN matrix grown on a sapphire substrate were investigated. The PL emission mechanism was shown to be governed by the quantum dot (QD)-like indium-rich areas with size about 3 nm, which was determined from high resolution transmission electron microscopy image analysis. The local indium composition in QDs of the samples was estimated as about 26% using the suggested model of PL transition energy, which accounts for quantum confinement energy, spontaneous and piezoelectric fields.