Visible Photoluminescence of Selectively Etched Porous nc-Si-SiOx Structures

The results of the first studies of the effect of selective etching on photoluminescence in porous nc-Si-SiOx structures containing Si nanoclusters (nc-Si) in the SiOx matrix are reported. In the initial samples at room temperature, intense photoluminescence bands are observed with peaks at 840 and 660 nm corresponding to radiative recombination of free charge carriers (or charge carriers bound to excitons) excited in nc-Si. After selective etching of the nc-Si-SiOx structures in 1% HF solution, these bands are noticeably shifted to higher energies of the spectrum. It is suggested that the evolution of the spectra is due to the decrease in the Si nanoparticle dimensions on etching of the oxide and additional oxidation of nc-Si. The results show that selective etching of the oxide matrix can be used to control the radiation spectra of porous nc-Si-SiOx structures.