Effect of Annealing Temperature on the Optical Spectra of CdS Thin Films Deposited at Low Solution Concentrations by Chemical Bath Deposition (CBD) Technique

Abstract

Two different concentrations of CdCl2 and (NH2)2CS were used to prepare CdS thin films, to be deposited on glass substrate by chemical bath deposition (CBD) technique. CdCl2 (0.000312 M and 0.000625 M) was employed as a source of Cd2+ while (NH2)2CS (0.00125 M and 0.000625 M) for S2− at a constant bath temperature of 70 °C. Adhesion of the deposited films was found to be very good for all the solution concentrations of both reagents. The films were air-annealed at a temperature between 200 °C to 360 °C for one hour. The minimum thickness was observed to be 33.6 nm for film annealed at 320 °C. XRD analyses reveal that the films were cubic along with peaks of hexagonal phase for all film samples. The crystallite size of the films decreased from 41.4 nm to 7.4 nm with the increase of annealing temperature for the CdCl2 (0.000312 M). Optical energy band gap (Eg), Urbach energy (Eu) and absorption coefficient (α) have been calculated from the transmission spectral data. These parameters have been discussed as a function of annealing temperature and solution concentration. The best transmission (about 97%) was obtained for the air-annealed films at higher temperature at CdCl2 (0.000312 M).

On the sub-band gap optical absorption in heat treated cadmium sulphide thin film deposited on glass by chemical bath deposition technique

“…The values of the absorption coefficient have been found to be in the range of 10 4 cm À1 in the Urbach region, which are in conformity with the results reported in a number of earlier works. 4,[18][19][20][21] The measured absorption coefficients are used to determine the band gap energy of the material by applying the relation a 2 ¼ A 2 (h À E g ), which corresponds to band-toband transition region near the absorption edge. As already discussed in Sec.…”

Effect of Annealing on the Properties of Nanocrystalline CdS Thin Films Prepared by CBD Method

“…It has been used as a window layer in high efficiency thin film solar cells base on cadmium telluride (CdTe), copper indium diselenide / sulphide (CIS) and copper indium gallium diselenide / sulphide (CIGS) [4]. It has been used in the deposition of CdS semiconductor thin films since the 1960s [5,6] and many techniques including electrodeposition [7,8], spray pyrolysis [9], successive ionic layer adsorption and reaction (SILAR) [10], vacuum evaporation [11], and Chemical Bath Deposition (CDB) [12][13][14]. CBD is known to be a simple method, with low temperature and inexpensive large area deposition technique, it use an aqueous solution and then we can control the chemical parameters of solution like (temperature, molar concentration, PH, time of deposition, stirring rate., etc.)…”

Direct on chip cadmium sulfide thin film transistors synthesized via modified chemical surface deposition

“…35 For instance, it has been reported that the decrease in lm resistivity is due to CdS oxidation (CdO), sulfur evaporation resulting in sulfur vacancies, removal of impurities, or morphological changes due to the grain growth with the concomitant reduction of grain boundaries. 35,[53][54][55] In order to understand the origin of the resistivity reduction aer annealing at 300 C for 60 min in air, the structural, physicochemical, and morphological properties of the lms reacted at 250 C with and without this additional annealing were studied. The results regarding thermal annealing in N 2 can be found in the ESI.…”