Effect of low-temperature interlayer in active-region upon photoluminescence in multiple-quantum-well InGaN/GaN

Abstract

Photoluminescence (PL) spectra dependent on the excitation power and temperature of two different red-emitting InGaN/GaN trapezoidal multiple quantum wells (TMQWs), with GaN and AlN low-temperature interlayers (LTILs) between the InGaN well and GaN barrier layers, were investigated. It was found that compared with the TMQWs with GaN LTILs, the TMQWs with AlN LTILs have a better structural quality, more significant carrier-localizing effect, and superior internal quantum efficiency. The results can be explained by the fact that due to the stability of Al–N bond and strain-compensated effect of AlN, compared with the GaN LTIL, the AlN LTIL grown on the InGaN well layer with embedded In-rich quantum dots (QDs), cannot only reduce threading dislocation densities as confirmed by XRC measurements, but also prevent In atoms from diffusing from In-rich QDs to InGaN matrix and/or from the InGaN well to GaN barrier layer, thus suppressing degradation of the QDs and generation of non-radiative centers.