Optical microcavities using highly luminescent films of semiconductor nanocrystals

Colloidally grown CdSe nanocrystals with epitaxial ZnS shells show highly e fficient, size-tunable luminescence. We report the incorporation of films o f these core-shell nanocrystals into wavelength-scale, high-Q, planar micro cavities. Under optical excitation, we find that emission from the nanocrys tals couples to the discrete optical modes of the microcavity. The broad fr ee-space emission spectrum of the nanocrystals is modified by the presence of the microcavity, giving a series of sharp emission lines with wavelength s determined by the cavity dimension. Our experiments demonstrate that micr ocavities with semiconductor emitters can be conveniently fabricated using spin-coating techniques. We find that, at room temperature, the microcavity emission spectrum is independent of excitation intensity for excitation de nsities up to approximately one electron-hole pair per nanocrystal. (C) 200 0 American Institute of Physics. [S0003-6951(00)02042-8].