Abstract: A process for controllably forming silicon nanostructures such as a silicon quantum wire array. A silicon surface is sputtered by a uniform flow of nitrogen molecular ions in an ultrahigh vacuum so as to form a periodic wave-like relief in which the troughs of said relief are level with the silicon-insulator border of the SOI material. The ion energy, the ion incidence angle to the surface of said material, the temperature of the silicon layer, the formation depth of the wave-like relief, the height of said wave-like relief and the ion penetration range into silicon are all determined on the basis of a selected wavelength of the wave-like relief in the range 9 nm to 120 nm. A silicon nitride mask having pendant edges is used to define the area of the silicon surface on which the array is formed. Impurities are removed from the silicon surface within the mask window prior to sputtering.