Abstract: A method of making semiconductor quantum wires employs a semiconductor wafer (14) as starting material. The wafer (14) is weakly doped p type with a shallow heavily doped p layer therein for current flow uniformity purposes. The wafer (14) is anodised in 20% aqueous hydrofluoric acid to produce a layer (5) microns thick with 70% porosity and good crystallinity. The layer is subsequently etched in concentrated hydrofluoric acid, which provides a slow etch rate. The etch increases porosity to a level in the region of 80% or above. At such a level, pores overlap and isolated quantum wires are expected to form with diameters less than or equal to 3 nm. The etched layer exhibits photoluminescence emission at photon energies well above the silicon bandgap (1.1 eV) and extending into the red region (1.6-2.0 eV) of the visible spectrum.