A.R. Babar

Gallium doping in transparent conductive ZnO thin films prepared by chemical spray pyrolysis

Zinc oxide (ZnO) and ZnO : Ga films have been deposited by the spray pyrolysis method onto preheated glass substrates using zinc acetate and gallium nitrate as precursors for Zn and Ga ions, respectively. The effect of Ga doping on the structural, morphological, optical and electrical properties of sprayed ZnO thin films were investigated using x-ray diffraction (XRD), scanning electron microscopy, optical absorption, photoluminescence (PL) and Hall effect techniques. XRD studies reveal that films are polycrystalline with hexagonal (wurtzite) crystal structure. The thin films were oriented along the (0 0 2) plane. Room temperature PL measurements indicate that the deposited films exhibit proper doping of Ga in ZnO lattice. The average transparency in the visible range was around ~85–95% for typical thin film deposited using 2 at% gallium doping. The optical band gap increased from 3.31 to 3.34 eV with Ga doping of 2 at%. The addition of gallium induces a decrease in electrical resistivity of the ZnO : Ga films up to 2 at% gallium doping. The highest figure of merit observed in this present study was 3.09 × 10−3 cm2 Ω−1.

Physical properties of sprayed antimony doped tin oxide thin films: The role of thickness

Transparent conducting antimony doped tin oxide (Sb:SnO2) thin films have been deposited onto preheated glass substrates using a spray pyrolysis technique by varying the quantity of spraying solution. The structural, morphological, X-ray photoelectron spectroscopy, optical, photoluminescence and electrical properties of these films have been studied. It is found that the films are polycrystalline in nature with a tetragonal crystal structure having orientation along the (211) and (112) planes. Polyhedrons like grains appear in the FE-SEM images. The average grain size increases with increasing spraying quantity. The compositional analysis and electronic behaviour of Sb:SnO2 thin films were studied using X-ray photoelectron spectroscopy. The binding energy of Sn3d5/2 for all samples shows the Sn4+ bonding state from SnO2. An intensive violet luminescence peak near 395 nm is observed at room temperature due to oxygen vacancies or donor levels formed by Sb5+ ions. The film deposited with 20 cc solution shows 70 % transmittance at 550 nm leading to the highest figure of merit (2.11 × 10−3Ω−1). The resistivity and carrier concentration vary over 1.22 × 10−3 to 0.89 × 10−3Ωcm and 5.19 × 1020 to 8.52 × 1020 cm−3, respectively.

Structural and optoelectronic properties of sprayed Sb:SnO2 thin films: Effects of substrate temperature and nozzle-to-substrate distance

The influence of substrate temperature and nozzle-to-substrate distance (NSD) on the structural, morphological, optical and electrical properties of Sb:SnO2 thin films prepared by chemical spray pyrolysis has been analyzed. The structural, morphological, optical and electrical properties were characterized by using XRD, SEM, UV-visible spectrophotometry and Hall effect measurement techniques. It was seen that the films are polycrystalline, having a tetragonal crystal structure with strong orientation along the (200) reflection. The pyramidal crystallites formed due to coalescence were observed from SEM images. The values of highest conductivity, optical transmittance and figure of merit of about 1449(Ω·cm)−1, 70 %and 5.2 × 10−3 □/Ω, respectively, were observed for a typical film deposited using optimal conditions (substrate temperature = 500 °C and NSD = 30 cm).

Photoelectrocatalytic activity of spray deposited ZnO thin films against E. coli Davis

Abstract Zinc oxide (ZnO) thin films have been deposited onto fluorine doped tin oxide coated glass substrates by economical chemical spray pyrolysis technique. Films were deposited using various quantities of solution from 50 to 200 cc (substrate temperature 400°C, solution concentration 0·2M) in order to achieve different thicknesses. The films were characterised by X-ray diffraction, SEM, AFM and optical absorption techniques. The films exhibit a hexagonal wurtzite crystal structure with preferred (002) orientation. Morphological study showed a smooth and nanocrystalline surface of ZnO films. Direct optical band gap energy of ZnO thin films is found to be 3·24 eV. The average transmission is of the order of 87% in the visible region. The photoelectrocatalytic response of the film against Escherichia coli Davis is studied using a specially designed photoelectrochemical (PEC) reactor module. Thickness and UV light dependent photoelectrocatalytic bactericidal properties of ZnO thin films have been investigated. It shows that biased 1·1 μm thick ZnO thin films with 2 mW cm−2 UV light intensity give better bactericidal response compared to others. The relative percentage of killing of bacteria is 19·81% due to UV illumination, 52·71% due to UV illumination and passing over ZnO surface and 95·03% due to UV illumination and passing through PEC reactor with ZnO thin film after 2·5 h. It can be concluded that the ZnO thin film with photochemical reactor can be used in a water purifier to get bacteria free drinking water.

(Photo) electrochemical investigations on spray deposited n-CdIn 2Se4 thin film/polysulphide/c photoelectrochemical solar cell1

Cadmium indium selenide (n-CdIn 2Se4) thin films have been synthesized by spraying the mixture of an equimolar solutions of cadmium chloride [CdCl2], indium trichloride [InCl3] and selenourea [(NH2)2CSe] in aqueous media onto preheated fluorine doped tin oxide (FTO) coated glass substrates at optimized parameters of substrate temperature and solution concentration. The photoelectrochemical (PEC) cell configuration of n-CdIn2Se/(l MNaOH + 1 MNa2S + 1 M S)/C has been used for investigating the current—voltage (I–V) characteristics under dark and white light illumination, photovoltaic output, spectral response, photovoltaic rise and decay characteristics. The PEC study reveals the thin film of CdIn2Se4 exhibits n-type conductivity. The junction quality factor in dark (nd) and light (nl), series and shunt resistance (Rs and Rsh), fill factor (FF) and efficiency (η) for the cell have been estimated. The observed efficiency and FF of PEC solar cell is found to be 1.95 and 0.37% respectively. Mott-Schottky plot shows the flat-band potential (V fb) of n-CdIn2Se4/(l M NaOH + 1 M Na2S + 1 M S)/C cell to be—0.655 V/SCE.