Sol–gel derived ZnO/porous silicon composites for tunable photoluminescence

ZnO/porous silicon nanocomposites were fabricated by spin-coating the sol–gels of zinc acetate onto the top surface of porous silicon films. The photoluminescent properties of ZnO/porous silicon nanocomposites were investigated as a function of the concentration of zinc cations in the sol–gels. Characterizations with scanning electron microscopy, X-ray diffractometry and photospectroscopy indicated that ZnO nanocrystals were embedded into the spongy nanostructures of porous silicon after heat treatment at 245 °C for 20 min in air. The recorded photoluminescence exhibited that orange to green–blue emissions were achieved for the ZnO/porous silicon nanocomposites as the concentration of zinc cations in the sol–gels increased from 4 to 260 mM. The mechanisms on the tunability of the photoluminescence were discussed for the ZnO/porous silicon nanocomposites. Our results have demonstrated that the incorporation of green–blue phosphors into the porous matrix of porous silicon represents one endeavor to tune the photoluminescence of porous silicon across the visible spectral region.