Fabrication of height-controlled InAs quantum dots on GaAs surfaces by in situ AsBr 3 etching and molecular beam epitaxy

Abstract

A technique for controlling the height of InAs quantum dots (QDs) on GaAs surfaces has been investigated by combining layer-by-layer in situ AsBr 3 etching and molecular beam epitaxy (MBE). One layer of InAs QDs in the Stranski–Krastanow (SK) growth mode is first formed on a GaAs surface by MBE. After a thin GaAs film is deposited on the InAs SK QDs, in situ etching creates an array of nanoholes on the etched GaAs surface. The nanoholes offer highly selective nucleation sites for the subsequent growth of InAs QDs. Finally, second-layer QDs are grown by providing InAs of only about 1 monolayer (ML). Atomic force microscopy surface observations indicate that a planar growth surface is obtained with the supplied amount of ∼1 ML of InAs. Cross-sectional structural observations conducted using a scanning transmission electron microscope and energy dispersive X-ray analysis reveal that vertically overlapping InAs QDs are achieved. These results demonstrate the formation of height-controlled InAs QDs.