Synthesis and Optical Characterization of GaAs Epitaxial Nanoparticles on Silicon

The integration of direct bandgap III-V materials on Si is one of the main bottlenecks on the way to cheap and highly efficient optoelectronic devices. The goal of this work is to study the formation and optical properties of GaAs nanoparticles synthesized on Si(111) by molecular beam epitaxy. It is demonstrated that GaAs tends to grow in the shape of faceted nanoparticles surrounded by the continuous layer of coalesced GaAs islands. The surface density and shape of the nanoparticles are strongly affected by the growth parameters. The nanostructures are studied via analysis of atomic force microscopy images to show their faceting with the {111}, {110}, and {3 (1) over bar1} - planes. Optical properties are studied by photoluminescence and Raman spectroscopy. Depending on the growth conditions, Raman spectra of individual epitaxial GaAs nanoparticles possess specific features typical for wurtzite GaAs, demonstrating the potential of the studied growth approach for the synthesis of the phase engineered nanostructures.