CdSe quantum dots in ZnSe nanowires as efficient source for single photons up to 220 K

Abstract

ZnSe nanowire heterostructures were grown by molecular beam epitaxy in the vapour–liquid–solid growth mode assisted by gold catalysts. Size, shape and crystal structure are found to strongly depend on the growth conditions. Both, zinc-blende and wurtzite crystal structures are observed using transmission electron microscopy. At low growth temperature, cone-shaped nano-needles are formed. For higher growth temperature, the nanowires are uniform and have a high aspect ratio with sizes of 1– 2 μ m in length and 20–50 nm in width as observed by scanning electron microscopy. Growing a nanowire on top of a nano-needle allows us to obtain very narrow nanorods with a diameter less than 10 nm and a low density of stacking fault defects. These results allow us the insertion of CdSe quantum dots in a ZnSe nanowire. An efficient photon anti-bunching was observed up to 220 K, demonstrating a high-temperature single-photon source.