Observation of Shape, Configuration, and Density of Au Nanoparticles on Various GaAs Surfaces via Deposition Amount, Annealing Temperature, and Dwelling Time.

Metallic nanoparticles have been widely witnessed in many applications: serving as the catalysts for various nanowire systems, as the active mediums of various device applications, and also for the nanoscale templates for hybrid quantum structures. In the performance of devices and configurations of the resulting nanostructures, the size and density of nanoparticles play critical roles. In this paper, the control of self-assembled Au droplets on GaAs (100), (110), and (111) is systematically investigated through the variation of deposition amount (DA), annealing temperature (AT), and dwelling time (DT). Based on the Volmer-Weber growth model, the formation of Au droplets and dramatic evolution of Au nanostructures on various GaAs surfaces is observed from the Au clusters to the round-dome shapes with the AT variation between 250 and 550 °C. With the systematic DA control, a radical size and density evolution of Au droplets shows the size expansion of over 400 % in average height and 800 % in average lateral diameter, while the density shows over two orders of decrease. With the DT variation, the self-assembled Au droplets tend to grow larger due to the Ostwald ripening while a clear distinction among the surface indexes is observed.