5. Ordering of Ga Nanodroplets by Low-Energy Ion Sputtering

Ordered nanostructures have attracted much attention due to their potential in realizing novel device applications. In this chapter, we present a study of ordered nanodroplets fabricated by low-energy ion sputtering on GaAs surfaces. The morphological evolution of a GaAs (001) surface exposed to a Ga⁺ focused ion beam was investigated as a function of beam energy, incidence, current, sputter time, and dwell time. The sputter yield of the target, surface roughness, amount of material deposited on the surface, and temperature of the substrate were evaluated. The experimental results show formation of self-assembled Ga metal droplets. Control over the size, density, and ordering of the droplets is possible for various sets of ion beam parameters. The arrays of ordered nanodroplets have potential application as templates as well as a local nanosource in molecular beam epitaxy for fabricating ordered semiconductor structures such as quantum dots.