Light-emitting structures of CdS nanocrystals in oxidized macroporous silicon

Abstract

Structured silicon substrates (macroporous silicon) with SiO2 nanolayers and CdS nanocrystals were proposed to reduce the flow of electrons and recombination outside the nanoparticle layer. It was found that the resonance electron scattering in samples with low concentration of SiOSi states transforms into ordinary scattering on ionized impurities for samples with high concentration of SiOSi states. The maximal intensity of photoluminescence was measured for a structure with maximum strength of the local electric field at the SiSiO2 interface, indicating a significant decrease of non-radiative recombination in CdS nanocoating due to the flow of electrons from the silicon matrix towards the CdS nanocrystal layer. The quantum yield of photoluminescence increases with time due to evaporation of water molecules.