Effect of layer thickness on the luminescence properties of ZnS/CdS/ZnS quantum dot quantum well

ZnS/CdS/ZnS quantum dot quantum well was prepared. The optical properties of ZnS/CdS/ZnS QDQW with different thickness of CdS well and ZnS shell were studied. Absorption spectra, emission spectra, and luminescence lifetimes were measured. The observed luminescence was assigned to the bulk donor-acceptor pair recombination of CdS and can be enhanced by increasing the thickness of the CdS well or coating an appropriate thickness of ZnS shell on the surface of the CdS well. The luminescence enhancement was caused by the relative reduce in the surface effect. The luminescence lifetimes were influenced strongly by the surface state.