Preparations of PbSe quantum dots in silicate glasses by a melt-annealing technique

Abstract

Silicate glass containing PbSe quantum dots (QDs) has important prospective applications in near infra-red optoelectronic devices. In this study, single-stage and double-stage heat-treatment methods were used respectively to prepare PbSe QDs in silicate glasses. Investigation results show that the double-stage heat-treatment is a favorable method to synthesize PbSe QDs with strong photoluminescence (PL) intensity and narrow full weight at half maximum (FWHM) in PL peak. Therefore, the method to prepare PbSe QDs was emphasized on the double-stage heat-treatment. Transmission electron microscopy measurements show that the standard deviations of the average QD sizes from the samples heat-treated at the development temperature of 550°C fluctuate slightly in the range of 0.6–0.8nm, while this deviation increases up to 1.2nm for the sample with the development temperature of 600°C. In addition, the linear relationship between the QD size and holding time indicates that the crystallization behavior of PbSe QDs in silicate glasses is interface-controlled growth in early stage of crystallization. The growth rates of PbSe QDs are determined to be 0.24nm/h at 550°C and 0.72nm/h at 600°C. In short, the double-stage heat-treatment at 450°C for 20h followed by heat-treatment at 550°C for 5h is a preferred process for the crystallization of PbSe QDs in silicate glass. Through this treatment, PbSe QDs with a narrow size dispersion of 5.0±0.6nm can be obtained, the PL peak from this sample is highest in intensity and narrowest in FWHM among all samples, and the peak is centered on 1575nm, very close to the most common wavelength of 1550nm in fiber-optic communication systems.