Growth of CdS:Cu Nanocrystals by Chemical Synthesis

Abstract

CdS:Cu nanocrystalline films were prepared by chemical bath on glass substrates at a deposition temperature of 80°C. Different Cu-doping levels were obtained by changing the volume of the Cu-reagent-solution into the CdS growing solution. X-ray diffraction ͑XRD͒ and optical absorption ͑OA͒ measurements were carried out to characterize the material. From the XRD patterns it is concluded that grains in undoped films grow in the wurtzite hexagonal phase, and in Cu-doped films they grow in the zinc blende cubic phase. The average grain size, located in the range 14-23 nm, was calculated by employing Scherrer's formula. From OA spectra the forbidden energy bandgap ͑E g ͒ was determined by using the ͑␣h͒ 2 ϰ ͑E g -h͒ relation, where ␣ is the OA-coefficient and h the photon energy. Due to the doping, E g shifts to lower values depending on the impurity level of the film. Furthermore, the dependence of E g with radius size and interplanar distances of the lattice is discussed. Gibbs free energy calculation for the Cu doping CdS process is also included.

Properties of PbS: Ni2+ Nanocrystals in Thin Films by Chemical Bath Deposition

“…As expected, UCV has a similar dependence with IDs versus V [Ni 2+ ] ; this type of plot has been reported when Cu 2+ in CdS is either decreasing or increasing [6]. To the best of our knowledge, no dependence between IDs and GS has been found in theoretical approaches and experimental findings on doped and undoped nanocrystals reported [6,21,22]. Figure 9 exhibits the (111) interplanar distance (ID) as function of the average GS, and in inset the 1/GS versus unit cell volume (UCV) is displayed.…”

“…It can be seen for the PbSNi0, GS ∼32 nm, that the GS decreases for doped samples. The effect of the GS decrease by the doping effect has been reported in films of CdS doped with Cu 2+ by CBD [6]. A decrease in the degree of order of crystallites is expected to lead to enhanced growth of stable nuclei at the initial stages of growth, followed by impaired grain growth, and hence resulting in smaller grains in the nickel.…”

“…As the Ni 2+ concentration is increased, the diffraction peaks become broader due to reduction in the grain size. At this level of V [Ni 2+ ] , the PbSNi can be considered a doped material [6]. The incorporation of Ni 2+ solubility has been proven to be more effective in Pb chalcogenide than Zn-chalcogenide, a result explained in terms of the cation size.…”

“…In this regard, many techniques have been successfully employed: successive ionic layer and reaction (SILAR) [3], sol gel methods [4], and so forth. Most of the studies reported so far have focused on the deposition of ternary derivatives material in thin films as Cd 1−x Zn x S [5], Cd 1−x SCu x [6], and Hg x Cd 1−x S [7]. Noteworthy is the fact that PbS thin films are promising photovoltaic materials as their variable E g can be adjusted to match the ideal ∼1.…”

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

“…The intensity change in (200) peak, as shown in the inserted pattern, highlights the strong dependency of crystallization on the content of Cu. It has been reported that Cu in the chemical bath deposition may have different reaction kinetics in forming the chalcogenide phase so that the involvement of Cu precursor acts negatively in the sulfide formation[23][24][25].…”