Enhanced spontaneous emission of CdSe quantum dots in monolithic II-VI pillar microcavities

The emission properties of $CdSe∕ZnSe$ quantum dots in ZnSe-based pillar microcavities are studied. All-epitaxial cavities made of ZnSSe and $MgS∕ZnCdSe$ superlattices with a single quantum-dot sheet embedded have been grown by molecular beam epitaxy. Pillar structures with diameters down to $500nm$ have been realized by focused-ion-beam etching. A pronounced enhancement of the spontaneous emission rate of quantum dots coupling to the fundamental mode of the cavities is found as evidence for the Purcell effect. The enhancement by a factor of up to 3.8 depends systematically on the pillar diameter and thus on the Purcell factor of the individual pillars.