Size-selected compound semiconductor quantum dots by nanoparticle conversion

We have developed a novel technology, called nanoparticle conversion, for producing compound semiconductor quantum dots (QDs) in which the dot size, surface density, position, and the materials system are all independently controlled. Nanoparticle conversion also lends itself to spatially controlled positioning of QDs. To demonstrate this technology we report the formation of InP QDs using nanoparticle conversion. We have produced QDs on substrates of different types by converting randomly and lithographically positioned nanoparticles into compound semiconductors in a chemical vapour deposition system. Electron microscopy and atomic force microscopy measurements reveal that the morphology of these QDs is similar to that of QDs produced by other techniques. Photo- and cathodoluminescence measurements show that the converted nanoparticles exhibit properties and behaviours typical of semiconductor QDs. These include quantum confinement, free-to-bound recombination and blinking. Production of multi-component QDs like InP, GaN, and InAsP on various substrates like Si, SiO2, and sapphire show that this technology can produce a wide variety of different types of QD on different substrates with minimal need for process optimization.