Structural, optical and electrical properties of PbS and PbSe quantum dot thin films

• Published in: Journal of materials science. Materials in electronics 2016-10, Vol.27 (10), p.10070-10077
• Main Authors: El-Menyawy, E. M., Mahmoud, G. M., Ibrahim, R. S., Terra, F. S., El-Zahed, H., El Zawawi, I. K.
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Charge carriers; Chemistry and Materials Science; Electrical properties; Electronics; Materials Science; Optical and Electronic Materials; Optical properties; Qunatum dots; Refractive index; Refractivity; Thin films; X-rays
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-016-5080-6

PbS and PbSe were prepared by hot injection method. The powders were used for preparing the corresponding films by using thermal evaporation technique. The structural, optical and electrical properties of PbS and PbSe thin films were investigated. The structural properties of PbS and PbSe were investigated by X-ray diffraction, transmission electron microscopy and energy dispersive X-ray techniques (EDX). PbS and PbSe films were found to have cubic rock salt structure. The particles size ranged from 1.32 to 2.26 nm for PbS and 1.28–2.48 nm for PbSe. EDX results showed that PbS films have rich sulphur content, while PbSe films have rich lead content. The optical constants (absorption coefficient and the refractive index) of the films were determined in the wavelength range 200–2500 nm. The optical energy band gap of PbS and PbSe films was determined as 3.25 and 2.20 eV, respectively. The refractive index, the optical dielectric constant and the ratio of charge carriers concentration to its effective mass were determined. The electrical resistivity, charge carriers concentration and carriers mobility of PbS at room temperature were determined as 0.55 Ω cm, 1.7 × 10 16  cm −3 and 656 cm 2  V −1 s −1 , respectively, and for PbSe films they were determined as 0.4 Ω cm, 9 × 10 15  cm −3 and 1735 cm 2  V −1 s −1 , respectively. These electrical parameters were investigated as a function of temperature.