Site control of InAs quantum dot nucleation by ex situ electron-beam lithographic patterning of GaAs substrates

Abstract

Conventional electron-beam lithographic patterning of GaAs substrates followed by reactive-ion etching of small holes has been successfully used to control the nucleation of InAs dots. We have observed > 50 % single dot occupancy for holes ∼ 60 nm wide and ∼ 35 nm deep and show that the dot occupancy and dot size can be varied by changing the size of the holes. Luminescence from an array of these site-controlled dots has been demonstrated. Thus this use of substrate patterning is a viable technique to controllably place single dots at pre-determined positions in devices.