Investigation of the cross-sectional morphology of epitaxial Si nanowires grown by chemical vapor deposition for the fabrication of vertical devices

•Surface morphology of vapour-liquid-solid self-assembly Si nanowires is examined.•Detailed TEM analysis shows inevitable surface roughening by the liquid AuSi catalysts during growth.•A method to reconstruct a smooth nanowire surface is demonstrated.•Useful information for fabricating vertical gate-all-around field-effect transistor devices is provided.