Light-emitting structures of CdS nanocrystals in oxidized macroporous silicon.

Abstract

Structured silicon substrates (macroporous silicon) with Si02 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 Si—0—Si states transforms into ordinary scattering on ionized impurities for samples with high concentration of Si—0—Si states. The maximal intensity of photoluminescence was measured for a structure with maximum strength of the local electric field at the Si—Si02 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.