Near-field photoluminescence imaging of single defects in a ZnSe quantum well structure at low temperatures

Summary form only given. The sample investigated here was grown by molecular-beam epitaxy on a 300-nm-thick GaAs buffer on a GaAs [001] substrate. This sample contains a single 4-nm-thin ZnSe quantum well with quaternary Zn/sub 1-x/Mg/sub x/S/sub y/Se/sub 1-y/ (ZnMgSSe) barriers with x/spl ap/0.1 and y/spl ap/0.1 on either side. The ZnMgSSe cap layer is only 17 nm thick and the ZnMgSSe barrier layer is 1000 nm thick. The sample surface reveals defects, which, in atomic force and electron micrograph images, show up as bow tie shaped structures with an extent of /spl ap/2 /spl mu/m. Their size distribution is very narrow and they are oriented with respect to crystallographic axes. The aim of the paper is to clarify the nature of the resulting potential landscape in the quantum well and the role of nonradiative carrier recombination in the well and the barriers by scanning near-field optical spectroscopy with a measured resolution of 200 nm at T=20 K.