Synthesis and near-IR-vis spectroscopic characterization of PbSeO3-encapsulated PbSe quantum dots

A novel method is suggested for the synthesis of PbSe semiconductor quantum dots (QDs) in PbSeO3 dielectric matrix via the oxidation of polycrystalline PbSe films in air at temperatures 25–500 °C. Raman and absorption spectroscopy characterization indicate that the variation of synthesis temperature affords the adjustment of the resulting QD size. Absorption spectra of the prepared films in the vis-NIR region involve numerous narrow bands corresponding to QDs of certain sizes. The increase of QD synthesis temperatures to 350 – 400 °С results in broadening of QD size distribution up to 1 – 9 nm due to a non-uniform oxidation at intergranular boundaries, while at 450 – 500 °C the particle size drops and stabilizes in a more narrow range of 2.5 – 3.5 nm, which can be accounted for the completion of oxidation and encapsulation of QDs in PbSeO3 matrix with termination of oxygen access. The bandgap values of the obtained samples estimated using Tauc method correspond to PbSe phase in the initial film and PbSeO3 phase in the oxidized state.