Growth of III-V Quantum Dots by Vapor-Liquid-Solid Epitaxy

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9304537 Sercel The formation of nanometer-scale III-V quantum dots by the vapor-liquid-solid (VLS) growth mechanism will be investigated. The basic goal of the research is to establish the feasibility of the process. Unlike previous approaches, the technique will produce quantum dots by mask-free epitaxy on the surface of a semiconductor substrate. Nanometer-scale group-III liquid metal droplets deposited on semiconductor substrates will be supersaturated with arsenic in a UHV deposition chamber, driving VLS growth of III-V quantum dots. The metal droplets will be placed on the growth substrate by two methods: (1) deposition of nanometer-scale metal clusters, and (2) melting of arrays of nanometer-scale metal dots formed by patterning thin metal films using electron-beam lithography. The latter method in particular will permit fabrication of regular arrays of GaAs and InAs quantum dots for production of periodic optical gain media. The absence of surface rnasking material will permit epitaxial growth of a wider band-gap encapsulation layer, and therefore, ultimate application of the technique to fabrication of devices such as the quantum dot semiconductor lasers. %%% The ability to directly synthesize three-dimensional semiconductor nanostructures, such as quantum dots, would enable realization of a number of predicted benefits. Applications which have been proposed for semiconductor quantum dot materials include use as an optical gain medium in semiconductor lasers, as a nonlinear medium for optical switching applications and in novel synthetic doping schemes. If the approach is successful, it will represent a new form of epitaxy with potentially great impact on optoelectronics technology. ***