Growth of doped PbS:Co²⁺ nanocrystals by Chemical Bath

Abstract

Nanocrystalline PbS films grown by chemical bath at $T = 40 \pm 2$ $^{\circ}$C onto glass slides were modified by in situ Co$^{2+}$ -doping and their structural and optical properties were examined. By FT-IR spectra, a sharp stretching mode can be seen at $ \sim\hspace{-3pt} 1384$ cm$^{-1}$ due to the vibration mode of CO$_{3}^{2}$ ions. XRD patterns shown the growth on the zinc blende crystalline face. The grain size was determined by using X-rays diffractograms and was found at $\sim\hspace{-3pt} 28$ nm and $\sim\hspace{-3pt} 13-25$ nm for undoped and doped samples, respectively. Optical absorption spectra was used for calculating the energy band gap, and displayed a shift in the $\sim\hspace{-3pt} 1.21-2.21$ eV range, associated with quantum confinement effect. Raman peaks at $\sim\hspace{-2pt} 210$, 271, and 451 cm$^{-1}$, corresponding to a 1LO phonon mode, a two-phonon process, and a 2LO phonon mode respectively were also recorded. The surface and grain size of the films were measured by AFM studies.