The modification of the radiative decay of a single emitter in close vicinity to a dielectric interface is investigated by studying the photoluminescence (PL) decay dynamics of colloidal semiconductor nanocrystals (NCs) deposited on semiconductor surfaces. The PL decay lifetimes of single CdSe/CdS NCs spin-coated on InP surfaces passivated with thin oxide layers are measured. Electrochemical passivation of the InP surfaces with oxide layers of different thicknesses enables to study the influence of the distance between the semiconductor surface and the NC on the lifetime. A shortening of the PL decay lifetimes of the NCs with respect to their lifetimes on glass strongly suggests the opening of recombination channels for the photogenerated exciton, which we attribute to energy transfer between the NC and the semiconductor. We also experimentally show the influence of the orientation of the NC with respect to the semiconductor surface on the coupling.