Formation of InSb quantum dots in a GaSb matrix using molecular-beam epitaxy

Abstract

InSb nanoislands in a GaSb matrix have been fabricated and their structural and luminescence properties have been studied. The deposition of ∼2 monolayers of InSb on the GaSb(100) surface has been found by atomic force microscopy to result in a 2D–3D growth mode transition and in a formation of 3D InSb islands with a size about 80 nm. Increase in the thickness of the InSb layer more than three monolayers causes a dramatic drop of the photoluminescence intensity due to plastical relaxation of the islands. Surprisingly transmission electron microscopy studies of InSb insertions with average InSb thickness below two monolayers demonstrate dense array of coherent 2D islands, or quantum dots, having a uniform lateral size of 30 nm. Bright luminescence due to these 2D islands is observed. We believe that these 2D multimonolayer islands can be used as precursor state for vertically coupled InSb-GaSb QD structures suitable for laser applications.