Triggering InAs/GaAs Quantum Dot nucleation and growth rate determination by in-situ modulation of surface energy

Epitaxial InAs/GaAs Quantum Dots (QDs) are widely used as highly efficient and pure sources of single photons and entangled photon-pairs, however reliable wafer-scale growth techniques have proved elusive. Growth of two-dimensional Quantum Well (QW) thin-films can be achieved with atomic precision down to below the de Broglie wavelength of electrons in the material, exposing the quantum particle-in-a-box energy vs. thickness-squared relationship. However, difficulties in controlling the exact moment of nanostructure nucleation obscure this behaviour in epitaxial QD material, preventing a clear understanding of their growth. In this work we demonstrate that QD nucleation can be induced by directly modulating the crystal surface energy without additional materials or equipment. This gains us quantitative measure of the QD growth rate and enables predictive design of QD growth processes. We believe this technique will be crucial to the realisation of uniform arrays of QDs required for scalable quantum devices at the single-photon level.