A convenient method has been developed to thin electron beam fabricated silicon nanopillarsunder controlled surface manipulation by transforming the surface of the pillars to an oxideshell layer followed by the growth of sacrificial ammonium silicon fluoride coating. The resultsshow the formation of an oxide shell and a silicon core without significantly changing theoriginal length and shape of the pillars. The oxide shell layer thickness can be controlled from afew nanometers up to a few hundred nanometers. While downsizing in diameter, smooth Sipillar surfaces of less than 10 nm roughness within 2 μm were produced after exposure tovapors of HF and HNO_3mixture as evidenced by transmission electron microscopy (TEM)analysis. The attempt to expose for long durations leads to the growth of a thick oxide whosestrain effect on pillars can be assessed by coupled LO–TO vibrational modes of Si-O bonds.Photoluminescence (PL) of the pillar structures which have been downsized exhibits visible andinfrared emissions, which are attributable to microscopic pillars and to the confinement ofexcited carriers in the Si core, respectively. The formation of smooth core–shell structures whilereducing the diameter of the Si pillars has a potential in fabricating nanoscale electronic devicesand functional components.
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