C.H. Bhosale

Structural and optical properties of electrodeposited Bi2S3, Sb2S3 and As2S3 thin films

Abstract Thin films of Bi2S3, Sb2S3 and As2S3 have been prepared by the electrodeposition technique from aqueous acidic baths using Na2S22O3 as a sulphide source. The films deposited from an EDTA-complexed bath are thin, uniform and adherent to the substrate. The electrodeposition potentials were estimated by polarization curves. The structural and optical properties of the films have been studied. The X-ray diffraction pattern of the films shows that they are polycrystalline. The estimated optical bandgap energies for Bi2S3, Sb2S3 and As2S3 are 1.58 eV, 1.74 eV and 2.35 eV respectively.

Optoelectronic properties of sprayed transparent and conducting indium doped zinc oxide thin films

Indium doped zinc oxide (IZO) thin films are grown onto Corning glass substrates using the spray pyrolysis technique. The effect of doping concentration on the structural, electrical and optical properties of IZO thin films is studied. X-ray diffraction studies show a change in preferential orientation from the (0 0 2) to the (1 0 1) crystal planes with increase in indium doping concentration. Scanning electron microscopy studies show polycrystalline morphology of the films. Based on the Hall-effect measurements and analysis, impurity scattering is found to be the dominant mechanism determining the diminished mobility in ZnO thin films having higher indium concentration. The addition of indium also induces a drastic decrease in the electrical resistivity of films; the lowest resistivity (4.03 × 10−5 Ω cm) being observed for the film deposited with 3 at% indium doping. The effect of annealing on the film properties has been reported. Films deposited with 3 at% In concentration have relatively low resistivity with 90% transmittance at 550 nm and the highest value of figure of merit 7.9 × 10−2 Ω−1.

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.

Preparation and characterization of electrodeposited Bi2Se3 thin films

Abstract Thin films of Bi 2 Se 3 have been prepared from an aqueous acidic bath at room temperature using selenium dioxide as a selenium ion source by a simple, inexpensive electrodeposition technique. The electrodeposition potentials for different bath compositions and concentrations are estimated from polarization curves. It has been found that Bi(NO 3 ) 3 and SeO 2 in the volumetric proportion as 7:3 and their equimolar solutions of 0.025 M form good quality films. The films are annealed in a nitrogen atmosphere at 200 °C for 2 h. The films are characterized by scanning electron microscopy, X-ray diffraction and optical absorption techniques. Studies reveal that as-deposited and annealed thin films are continuous and polycrystalline in nature. The optical band gap has been found to be 0.55 eV for the above-mentioned composition and concentration of the film.

Preparation and characterization of Bi2S3 thin films spray deposited from non-aqueous media

Abstract Semiconducting Bi 2 S 3 thin films were prepared on glass substrates from non-aqueous media using spray pyrolysis. Characterization of the films was carried out using X-ray diffraction, scanning electron microscopy, optical absorption and dark resistivity techniques. These studies reveal that as-deposited films are polycrystalline, having an optical band edge (direct) of 1.92 eV. The electrical resistivity is of the order of 10 6 Ω cm.

Preparation and properties of sprayed antimony trisulphide films

Abstract Semiconducting Sb 2 S 3 thin films have been prepared on glass substrates by spray pyrolysis. The films were deposited at optimised conditions of substrate temperature and solution concentration and have been characterised for their structural, optical and electrical properties. The films are semiconducting and amorphous. From the optical absorption study, the (indirect) bandgap is estimated to be 1.55 eV.

Preparation and characterization of spray deposited Sb2S3 thin films from non-aqueous medium

Abstract Semiconducting Sb2S3 thin films were prepared on glass substrate from non-aqueous medium using the spray pyrolysis technique. The films were deposited at the optimized substrate temperature and solution concentration. The films were characterized by means of X-ray diffraction, scanning electron microscopy, optical absorption and dark resistivity techniques. These studies revealed that as-deposited films are polycrystalline in nature with an optical band gap (direct) of 1.8 eV and electrical conductivity in the order of 10−6-10−7 ohm−1 cm

Characterisation of chemically converted sprayed Bi2O3 to Bi2S3 thin films

Abstract Bi2O3 thin films have been prepared by spray pyrolysis method onto the glass substrates at optimised substrate temperature of 450 °C. The spray rate was maintained to be constant during the deposition. These films have been converted into Bi2S3 thin films by a chemical method. The Bi2O3 thin films when dipped into a solution of sodium sulphide [Na2S] are found to be converted into Bi2S3 thin films. The structural, optical and electrical properties of both the Bi2O3 and Bi2S3 thin films are reported.

Photoelectrochemical studies on electrodeposited Cd-Fe-Se thin films

Thin films of Cd-Fe-Se have been prepared onto stainless steel substrates, for various compositions of Cd and Fe and solution concentrations by an electrodeposition technique. Cd 0.9 Fe 0.1 Se films, electrodeposited with a solution concentration of 10 mM, forming a photoelectrochemical (PEC) cell using ferri-ferrocyanide electrolyte, show a better PEC performance. The films deposited using optimized composition (9:1:10), solution concentration (10 mM), deposition time (30 min) and current density (1 mA/cm 2 ) have been used for further characterization by X-ray diffraction (XRD) and PEC techniques. It has been found that the as-grown films are polycrystalline in nature with orientations along the peaks of hexagonal CdSe and FeSe. It has also been found from the current-voltage and power output characteristics that n-Cd-Fe-Se/ferri-ferrocyanide junctions show good rectifying nature and the efficiency of the n-Cd 0.9 Fe 0 1 Se/ferri-ferrocyanide/C PEC cell is 0.41% with FF 50%.

A comparative study of concentration effect of complexing agent on the properties of spray deposited Sb2S3 thin films and precipitated powders

Abstract Sb2S3 semiconducting thin films and precipitated powders have been prepared by a spray pyrolysis technique and bulk precipitation method, respectively. The concentration of solution is kept constant at 0.1 M and only the concentration of complexing agent (tartaric acid) is varied from 0.25 M to 1 M. The thickness of the film measured by weight difference method is found to be relatively higher for the film deposited with 0.5 M tartaric acid. The film thickness is of the order of 0.1 μm. As-deposited films are found to be uniform, dark grey and well adherent to the glass substrates. In contrast, the precipitated powders are orange in colour. X-ray diffraction studies reveal that the precipitated powders are polycrystalline whereas films are amorphous in nature. Also it has been found that the crystallinity of the precipitated powder is higher for 0.25 M concentration and decreases for the further concentrations of complexing agent. The direct bandgap of the thin films is found to be 2.7 eV irrespective of concentration of complexing agent, whereas the direct bandgap of the precipitated powder varies from 1.92 to 2.02 eV and is found to be higher (2.02 eV) for the powder prepared using 0.75 M tartaric acid. Electrical resistivity study reveals that at 0.5 M tartaric acid, the R.T. resistivity of the thin film is relatively lower (∼ 106 Ωcm) than that of precipitated powder (∼ 10su8–109 Ωcm).