Influence of lattice relaxation on the properties of ZnSe/ZnS single quantum wells by MOVPE

The growth of ZnSe/ZnS single quantum well (SQW) structures was performed by atomic layer epitaxy (ALE) in an atmospheric pressure metalorganic vapour phase epitaxy (MOVPE) system. Through the photoluminescence measurement of ZnSe/ZnS SQWs, we observed clear shifts of the excitons to higher energies with decreasing well width, which demonstrate effects of strain and quantum confinement. Transition energies were calculated considering (i) a simple square well potential and (ii) a parabolic potential model under the action of strain effects. From comparison of the exciton energy with the calculated transition energies, we conclude that lattice relaxation induced interdiffusion occurs as the well width becomes thicker than the critical thickness.