Preparation and properties of (CdS) x -(PbS)1 −x thin-film composites

Abstract

A modified chemical deposition process is employed for the preparation of thin-film (CdS)~-(PbS)I-x composites with 0"2 ~< x ~< 0'8. Cadmium sulphate, lead acetate and thiourea are used as the basic source materials. The electrical conductivity is found to decrease with increasing composition parameter x up to 0"5 and increase for further increase in x. The composites are polycrystalline as is revealed from XRD and microscopic observations and show phases of both cubic and hexagonal CdS, cubic CdO and PbS, and tetragonal PbO and PbO2. Additional peaks of free elemental Cd and S have also been observed. For all the phases no significant variation in lattice parameters with x has been observed. The optical absorption studies show the presence of four well-defined absorption edges at approximately 0"45 eV, 1"05 eV, 1.80eV and 2'35 eV, at the same energies for all x values. The absorption coefficient is of the order of 104cm-1 and mode of band-to-band transition is of the direct type.

Effect of double substitutions of Cd and Cu on optical band gap and electrical properties of non-colloidal PbS thin films

“…The increased dark resistivity was 80.8 Ω·cm for the x=0.3 film (compared to 52.7 Ω·cm for x=0) that exhibited a substantially decreased mobility of 2.9 cm 2 /V·s. The increased resistivity with Cd may also result from the higher density of grain boundary since the grain boundary impedes the charge conduction by acting as scattering centers [22].…”

Studies on thin films of lead chalcogenides

“…Chalcogenides, especially, of cadmium, lead and zinc have proved their potential as efficient absorbers of electromagnetic radiation [1][2][3]. Lead chalcogenides (PbS, PbSe and PbTe) and their alloys have been the subject of considerable research due to the technological importance of these materials, in crystalline and polycrystalline forms, as detectors of infrared radiation and more recently as infrared emitters and solar control coatings also [4][5][6][7][8].…”

Effect of indium doping on (CdZn)Se composite thin films

“…This is due to filling of low lying energy level by conduction electron and segregation of the impurity along the grain boundary [29]. A plot of (˛h ) 2 versus h should be a straight line whose intercept to the x-axis gives the optical band gap.…”