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

Abstract

The CdS thin films were deposited on glass substrate by chemical bath deposition (CBD). The effect of annealing temperature on the morphological, structural, optical and electrical properties of the crystalline CdS films were investigated for different annealing temperature (as deposited, 300, 400 and 500 °C).The annealing time is 1 h. The materials have been prepared using simple aqueous solutions containing cadmium sulfate, as source of cadmium, and thiourea as source of sulfur and ammonium hydroxide as the complexing agent. The temperature of the bath was maintained at low temperature of 80 °C. The surface morphological properties studied by SEM and AFM respectively. The structural properties of CdS thin film was studied by X-ray diffraction. The optical parameter such as transmittance and energy band gap of the films with thermal annealing temperature was investigated by UV-Visible spectrophotometer. The variation of band gap values of CdS thin film samples were found to be in the range of 2.37 to 2.5 eV. Electrical resistivity measurements were carried out in four-probe Van Der Pauw geometry at room temperature by the Hall measurement. SEM image confirmed that film of smooth surface morphology.

Effect of vanadium pentoxide concentration in ZnO/V2O5 nanostructured composite thin films for toluene detection

“…The band gap (E g ) was determined by extrapolating the linear portions to the horizontal photon energy axis. 24,25 The calculated optical band gaps of the pure ZnO and ZnO/V 2 O 5 composite thin lms are tabulated in Table 3. The band gap decreased as the concentration of vanadium pentoxide increased.…”

Properties of Undoped and (Al, In) Doped ZnO Thin Films Prepared by Ultrasonic Spray Pyrolysis for Solar Cell Applications

“…The grain size (D) of undoped and (Al, In) doped ZnO thin films were evaluated to be between 12 nm to 15 nm by using the Debye Scherrer's formula [21]. 3Where  is the full width at half maximum (FWHM) of the diffraction peak;…”

“…A maximum transmittance of 85 % is obtained for undoped ZnO films at around 600 nm, whereas both the IZO and AZO films exhibit a maximum of 80 % at the same wavelength. The energy gap (Eg) of the ZnO films can be calculated by using the relation [26]:…”

“…where «K» is a constant, «h» is Planck's constant and Eg is the band gap energy. The absorption coefficient () which is a function of the photon energy (hν) is calculated from the optical transmittance spectra results using the following equation [27]:…”

Calculation of the thickness and optical constants of lead titanate thin films grown on MgO from their transmission spectra

“…The direct band gap is determined using this equation when linear portion of (h)² against h plot is extrapolated to intersect the energy axis at  =0 (Fig. 5) [31,32]. We have found that the value of the energy band gap of the PbTiO3 thin film deposited on MgO is 3.2 eV.…”