Nanostructured CdS prepared on porous silicon substrate: Structure, electronic, and optical properties

Nanostructured CdS was deposited electrochemically on porous silicon (PS) substrate/cathode. The PS-supported CdS deposits were found to be uniformly packed particles of ∼100 nm, each of which is an aggregate of smaller clusters of several nanometers as revealed by scanning electron microscope and confirmed by glancing incidence x-ray powder diffraction. No significant CdS deposition into the pore of porous silicon is found under the reported experimental conditions. X-ray absorption fine structures (XAFS), both extended x-ray absorption fine structure and x-ray absorption near edge structures, across the S and the Si K edge of the samples have been investigated. The structure and electronic properties of the CdS/PS composite are discussed on the basis of the XAFS results obtained using multichannel detection (total electron and x-ray fluorescence yields) from a series of CdS and PS samples. The optical luminescence behavior of CdS/PS was also investigated utilizing a technique often referred to as synchrotron x-ray excited optical luminescence (XEOL). By selecting excitation photon energies near the Si and the S K edge, the luminescence originated from both CdS and PS can be distinguished in the XEOL spectra.