Buried CdTe/CdMgTe single quantum dots using selective thermal interdiffusion

Individual buried CdTe/CdMgTe quantum dots (QDs) with diameters down to 140 nm have been realized using a novel technique of selective intermixing. Si O2 masks are defined by high-resolution electron beam lithography and a sub sequent annealing step causes a lateral selective interdiffusion between Cd and Mg atoms beneath the SiO2 masks. This results in a lateral modulation of the bandgap with a confinement potential of up to 270 meV, Photoluminesc ence studies of single QDs confirm the quasi-three-dimensional confinement of excitons, which is evidenced by a pronounced linewidth narrowing, the fo rmation of biexcitons and the observation of excited state emission.