Understanding the dynamics and ordering of (111) semiconductor surfaces is of fundamental importance for 1D nanostructure growth as they are the growth planes of the most prominent nanowire systems[1]. GaP(111) is for example the basis of the GaP nanowire trees and important light emitting nanowire structures[2,3]. The growth of 1D nanostructures from semiconductor surfaces are governed by the dynamics and structures found on length scales from sub-nanometer to microns. However these processes are far from understood and much experimental work is yet to be done.
We have investigated the ordering of the GaP(111) surface from the micron to the atomic scale using Low Energy Electron Diffraction (LEEM), Synchrotron based X-ray Photo Emission Electron Microscopy (XPEEM) and Scanning Tunneling Microscopy (STM). We find that upon initial removal of the native oxide on GaP(111) and formation of a six-fold domain structure, Ga droplets starts to form on the surface. The droplets moves across the GaP surface as they grow, and in their trail a dramatic ordering of the surface occur. While the atomic scale structure is not altered, the domain sizes increase significantly in the path of the Ga droplets. We directly follow the dynamics of the Ga droplets as they form and move across the surface and we image the resulting structures down to the atomic scale. We find that the droplet movement is influenced by the surface step morphology, and their stability depends on temperature and droplet size. We finally show that the movement and domain formation of the Ga droplets can be qualitatively altered by adsorbing Au nanoparticles on the surface.
[1] L. Samuelson, Mater. Today 6, 22–31 (2003)
[2] K. Dick et al, Nature Mat., (2004)
[3] Svensson C P T, et al. , Nanotechnol 16, 936-939 (2005)
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