Preparation and properties of transparent conductive aluminum-doped zinc oxide thin films by sol-gel process Abstract. Thin films of TiO 2 have been deposited on well cleaned glass substrates by Sol-Gel dip-drive coating technique. The films have been prepared at three different pH values (3, 5, and 9) of Sol and annealed in muffle furnace at three distinct temperatures (350 °C, 450 °C, and 550 °C) for one hour and are allowed to cool to room temperature. The films were characterized by XRD, EDAX, SEM and UV-Vis Spectrophotometer. The as deposited films were found to be amorphous in nature. The annealed films exhibit anatase in crystalline structure. The EDAX results have shown that all the films are maintained with TiO 2 in composition. The XRD results reveal that they are nano-crystalline in nature and the crystalline nature increases with annealing temperature and pH of the Sol. The transmittance and absorbance spectra have shown that the films are transparent and band gap of the films are of the order of 3 eV. The ab initio studies of TiO 2 (using GGA) was performed with Vienna ab initio Simulation package and the band structure and effective masses of the electrons and holes were determined.

The molecular flow in the hot wall epitaxial system has been studied by computer simulation using the Monte Carlo technique for the deposition of CdTe thin films. The number of wall collisions, intermolecular collisions, direct transmissions, number of molecules and flux density distributions along each volume of the tube, with different source temperatures and wall temperatures for various lengths and radii of the hot wall setup, have been simulated, then the optimal deposition conditions for the thermodynamic equilibrium of vapour transport are determined and experimentally validated.

No abstract

Bulk compounds of CdTe, Cd0.25Sn0.75Te and Cd0.25Te0.75Sn have been prepared by direct reaction of their high purity (99.9999%) elemental constituents employing rotating furnace. The hot wall system is optimized for the deposition of prepared alloys by using molecular flow studies with Monte Carlo simulation technique. Thin films have been deposited on well cleaned glass substrates using the prepared alloys by the optimized hot wall vacuum evaporation system. The compositions of the prepared bulk and thin films have been identified using energy dispersive X-ray analysis. The compositions are found to be same for both the bulk and thin films as the prepared alloys. The structural properties of the deposited films have been studied using X-ray diffraction technique. The results show that all the films are crystalline in nature and the peaks in the XRD graph of CdTe correspond to cubic zinc blende structure and that of Cd0.25Sn0.75Te and Cd0.25Te0.75Sn compounds to rock salt structure. The lattice parameters and grain sizes of all the films have been evaluated. The surface morphology of the thin films is studied using Scanning Electron Microscope (SEM). The SEM analysis shows that surface of the films are smooth and crystalline in nature. The optical transmittance spectra of thin films were recorded using spectrophotometer in the range of wavelength from 190 nm to 2500 nm. All the films exhibit direct optical band gap and their values are 1.45eV (CdTe), 0.9eV (Cd0.25Sn0.75Te) and 1.1eV (Cd0.25Te0.75Sn). Thicknesses of the thin films have been determined by multiple beam interferometric technique.

CdTe and CdSn3Te4 compounds were prepared by direct reaction of their high purity elemental constituents using rotating furnace. Optimal deposition conditions for the deposition of CdTe and CdSn3Te4 thin films in hot wall evaporation setup were simulated using Monte Carlo technique. Thin films of CdTe and CdSn3Te4 were deposited on glass substrates by hot wall evaporation method. From the XRD measurements it was found that the films of CdTe and CdSn3Te4 were of cubic zinc-blende and rock salt structures respectively. The lattice parameters were determined as a = 6.476 A (CdTe) and a = 6.238 A (CdSn3Te4) from the XRD data. The UV-Vis-NIR optical transmittance spectra of thin films of different films were obtained and it was found that the direct optical band gaps were 1.4 eV (CdTe) and 0.8 eV (CdSn3Te4). Electronic structure, band parameters and optical spectra of CdTe and CdSn3Te4 were calculated from ab initio studies within the GGA approximation. The experimental results were in good agreement with the theoretical values.