Site-Control of InAs Quantum Dots using Ex-Situ Electron-Beam Lithographic Patterning of GaAs Substrates

Abstract

Conventional e-beam lithography followed by either dry or wet etching of small holes in GaAs substrates has been used to control the position of InAs self-assembled quantum dots. The dependence of hole occupancy on both hole area and hole depth has been investigated. We show a range of hole sizes where greater than 30% of sites contain a single dot with up to 60% single dot occupancy seen for dry-etched holes ∼60 nm wide, ∼35 nm deep and for wet-etched holes ∼90 nm wide, ∼20 nm deep. Single dot luminescence from these placed dots is demonstrated despite only a 10 nm GaAs buffer between dots and regrowth interface.