Photoluminescence characterization of InGaN/InGaN quantum wells grown by plasma-assisted molecular beam epitaxy: Impact of nitrogen and galium fluxes

The impact of Ga and N fluxes on optical quality of InGaN multiple quantum wells grown by plasma assisted molecular beam epitaxy is studies by means of photoluminescence (PL) and time resolved photoluminescence (TRPL) technique. This investigation reveals that both PL spectrum intensity and broadening are affected by Ga and N fluxes but the optimal growth conditions for the smallest broadening and highest intensity can be different. These effects are explained by the changes in the concentration of nonradiative recombination centres. The experimental results are supported by simulation via hopping excitons model. The theoretical studies of impact of quantum wells inhomogeneity and concentration of nonradiative centres on photoluminescence intensity, decay times and quenching are presented and discussed. Both experimental and theoretical results show that nonradiative processes are present also at low temperature and the recombination efficiency can be lower than 100% even at low temperatures. (C) 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim