Site-control of InAs quantum dots using ex-situ electron-beam lithographic patterning of GaAs substrates

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 similar to 60 nm wide, similar to 35 nm deep and for wet-etched holes similar to 90 nm wide, similar to 20 nm deep. Single dot luminescence from these placed dots is demonstrated despite only a 10 nm GaAs buffer between dots and regrowth interface.