Electroluminescence and Spectral Shift of CdS Nanoparticles on Si Wafer

Abstract

Preparation of CdS nanoparticles, devices fabrication, and electroluminescence properties at room temperature of CdS nanoparticles on silicon substrates are reported. A spectral shift of 86-meV of free exciton transition was observed that was due to the passivation of p-hydroxyl thiophenol molecules around nanoparticles. Controlled process conditions such as heat treatment and/or with oxygemrrich environment are experimented and found to have significant influences on emission spectra. Radiative recombination corresponding to oxygen-impurity level, 273 meV below bandgap energy, presents in samples prepared in oxygen-rich environment In addition to such mechanism, coalescence of nanoparticles into bulk form also exists and contributes to enhanced luminescence.