Method for producing a nanostructure and nanostructures

A nano structure formed on the surface of a substrate containing Si and having a pattern of at least 2 μm in depth, in which Ga or In is contained in the surface of the pattern, and the Ga or the In has a concentration distribution that an elemental composition ratio Ga/Si or In/Si of Si and Ga or In detected by an X-ray photoelectron spectroscopy is at least 0.4 atomic percent in the depth direction of the substrate, and the maximum value of the concentration is positioned within 50 nm of the surface of the pattern.