Site-control of InAs quantum dots on InP by droplet epitaxy in MOVPE

We demonstrate a novel approach for site-controlled growth of InAs quantum dots on InP substrates emitting at telecom wavelengths, including the C-band, for quantum photonics applications. Regular nanohole arrays were defined by electron-beam lithography and dry etching, followed by InP regrowth. Quantum dots were then formed via droplet epitaxy in MOVPE, in which indium droplets were localised within the nanoholes and subsequently crystallised into site-controlled InAs quantum dots. Micro-photoluminescence measurements on a quantum dot array (2.5 µm pitch over 14 × 14 sites) reveal single-line emission in the telecom bands, with narrow linewidths reaching the instrument resolution, approximately 50 µeV for 60% of the dots and a single dot occupancy for over 80% of the nanoholes in the array.