Leveraging Crystal Anisotropy for Deterministic Growth of InAs Quantum Dots with Narrow Optical Linewidths

Abstract

Crystal growth anisotropy in molecular beam epitaxy usually prevents deterministic nucleation of individual quantum dots when a thick GaAs buffer is grown over a nanopatterned substrate. Here, we demonstrate how this anisotropy can actually be used to mold nucleation sites for single dots on a much thicker buffer than has been achieved by conventional techniques. This approach greatly suppresses the problem of defect-induced line broadening for single quantum dots in a charge-tunable device, giving state-of-the-art optical linewidths for a system widely studied as a spin qubit for quantum information.