Photoconductive properties of nanometer-sized Si dot multilayers

Nanometer-sized Si dot multilayers have been prepared by repeating a sequence of low-pressure chemical vapor deposition for dot formation and thermal oxidation for dot isolation. For the multilayer with Si dots in the range of 3–5 nm, the onset of photoconductivity is observable at a photon energy of 2 eV, corresponding to the optical absorption edge of the Si dots. This result indicates that the nanometer-sized Si dot multilayers are promising as photoconductors that work at various wavelengths because the optical band gap can be varied by controlling the dot size.