InP Ring-Shaped Quantum Dot Molecules by Droplet Epitaxy

Abstract

Droplet epitaxy technique is a key fabrication method to create ring-shaped nanostructures. InP ring-shaped quantum dot molecules are grown on In0.5Ga0.5P/GaAs(0 0 1) due to lattice mismatch of 3.8% between InP and In0.5Ga0.5P and isotropic migration property of In atoms during the crystallization step of In droplets on In0.5Ga0.5P. The ring shape, density of the ring and number of dots on the ring are controlled by various growth parameters such as deposition and crystallization temperatures, In deposition rate and thickness. InP ring-shaped quantum dot molecules provide photoluminescence peak at 740 nm (1.66 eV) with FWHM of 45 meV at 20 K. Potential applications of ring-shaped quantum dot molecules in quantum cellular automata are discussed.