title: Synthesis and characterization of nanoparticle thin films of a-(PbSe)100-xCdx lead chalcogenides.
abstract: We report the synthesis of amorphous (PbSe)100-xCdx (x = 5, 10, 15, and 20) nanoparticle thin films using thermal evaporation method under argon gas atmosphere. Thin films with a thickness of 20 nm have been deposited on glass substrates at room temperature under a continuous flow (50 sccm) of argon. X-ray diffraction patterns suggest the amorphous nature of these thin films. From the field emission scanning electron microscopy images, it is observed that these thin films contain quite spherical nanoparticles with an average diameter of approximately 20 nm. Raman spectra of these a-(PbSe)100-xCdx nanoparticles show a wavelength shift in the peak position as compared with earlier reported values on PbSe. This shift in peak position may be due to the addition of Cd in PbSe. The optical properties of these nanoparticles include the studies on photoluminescence and optical constants. On the basis of optical absorption measurements, a direct optical bandgap is observed, and the value of the bandgap decreases with the increase in metal (Cd) contents in PbSe. Both extinction coefficient (k) and refractive index (n) show an increasing trend with the increase in Cd concentration. On the basis of temperature dependence of direct current conductivity, the activation energy and pre-exponential factor of these thin films have been estimated. These calculated values of activation energy and pre-exponential factor suggest that the conduction is due to thermally assisted tunneling of the carriers.
authors.affiliation: Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia. alveema@hotmail.com.
authors.forename: M A
authors.initials: MA
authors.lastname: Alvi
authors.forename: Zishan H
authors.initials: ZH
authors.lastname: Khan
references.citation: Phys Rev B Condens Matter. 1993 Mar 15;47(12):7213-7226
references.pmid: 10004719
references.citation: Nanoscale Res Lett. 2010 Jun 27;5(9):1512-1517
references.pmid: 20730131