The effect of indium concentration on the optical properties of a-plane InGaN/GaN quantum wells grown on r-plane sapphire substrates

Abstract

We report on the optical properties of a series of non-polar a-plane InGaN/GaN multiple quantum well (QW) structures of constant well width and varying indium concentration. The emission spectrum is dominated by recombination at regions of the QW intersected by basal plane stacking faults. The peak energy of this emission red-shifts and the emission line width increases significantly with increasing average indium content in the QWs and indium-alloyed basal-plane stacking faults. Furthermore, the spectral sensitivity of the luminescence decay time weakens as the indium content of the sample increases. These effects are attributed to the increase in compositional and hence electronic disorder of higher indium content samples resulting in stronger carrier localisation, which suppresses relaxation within the band of localised states. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.