Wavelength tunable photoluminescence of ZnO/porous Si nanocomposites

ZnO/porous Si (PS) nanocomposite films were prepared with the sol–gel spin-coating method. The morphologies, crystal structures, chemical compositions, surface passivations and photoluminescence (PL) spectra of the ZnO/PS nanocomposite films were investigated. It is found that the PL of the ZnO/PS nanocomposites can be tuned from red to green–blue by increasing the concentration of zinc cations in the sol–gels from 7.5 to 240 mM. Post-thermal annealing of the ZnO/PS nanocomposite films at 600 °C can shift the PL further into violet–blue. The roles of SiO2 thin interfacial layer between the ZnO and the Si nanocrystals in the nanocomposites are discussed. Our work provides an affordable means of tuning the emission color of the ZnO/PS nanocomposites across the visible spectral region.