Abstract
We present a growth technique, which combines molecular beam epitaxy of ZnSe and externally wet-chemically prepared, colloidal NCs of CdSe to achieve fully integrated monolithic epitaxial heterostructures. Our results show that wet-chemically prepared semiconductor nanocrystals can be incorporated in an epitaxally grown crystalline cap layer. We investigated CdSe core, CdSe/ZnSe and CdSe/ZnS core/shell nanocrystals (NCs) overgrown with cap layers of ZnSe, where the thickness was varied between 20-40 nm. In this paper we discuss PL measurements of overgrown NCs as a function of the cap layer thickness and compare the results with the PL of NCs in solution. A distinct blue shift of the PL is observed when the core/shell dots are overgrown by ZnSe. We present a model which explains this blue shift as resulting from dissolution of the shell of the dots during the overgrowth. (c) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim