Cooling-path-selected self-assembly of telecom InAsP quantum dots

Abstract

Epitaxial quantum dots are leading solid-state sources of quantum light, but reproducible growth on indium phosphide (InP) remains challenging because dot-formation windows are narrow and emission wavelengths are difficult to predict. Here we report a new epitaxial route for InAsP quantum dots on InP(001), in which the cooling path selects the final morphology without intentional deposition of group-III dot material. High-temperature As exposure forms a shallow near-surface InAsP layer through As-P exchange; the cooling path and continued As supply determine whether three-dimensional islands form. Surface-sensitive spectroscopy shows near-surface As enrichment, while cross-sectional STEM/EELS identifies graded, As-rich InAsP islands. The capped emitters span 1.2-1.6 micrometers, with single-photon emission observed up to 100 K. Across 20 wafers, the surface-effective exchange dose D provides a practical calibration for targeting the median emission wavelength. These results establish cooling as an active epitaxial step for telecom InAsP quantum-dot formation and wavelength control.