M. D. Uplane

Structural, optical and electrical studies on spray deposited highly oriented ZnO films

Abstract Thin films of Zinc oxide (ZnO) have been prepared on glass substrates by spray pyrolysis techniques using 0.025 M aqueous solution of Zinc acetate. X-ray diffraction (XRD) reveals that the films are polycrystalline in nature having hexagonal wurtzite type crystal structure. The room temperature resistivity is of the order of 10 −1 Ω cm. Estimated band gap energy from optical absorption data is around 3.27 eV. Thermoemf measurements show that films are of n -type.

Growth of Bi2S3 film using a solution-gas interface technique

Abstract Uniform large-area Bi2S3 films about 0.3 μm thick were prepared using a solution-gas interface technique. The surface of a Bi(NO3)3 solution was exposed to H2S gas and a thin solid film was formed. The electrical and optical properties of films prepared in this way were studied. The band gap energy of Bi2S3 films estimated from electrical measurements was found to be in fair agreement with the value estimated from the optical measurements.

Deposition of highly oriented ZnO films by spray pyrolysis and their structural, optical and electrical characterization

Abstract Thin films of zinc oxide (ZnO) have been deposited onto glass substrates using a simple and inexpensive spray pyrolysis technique. A nonaqueous methanolic solution of zinc acetate was used as a spraying solution. The concentration of the solution was varied between 0.025 to 0.4 M. The films prepared at different solution concentrations were uniform and well adherent to the substrates. X-ray diffraction (XRD) studies showed that all the films were polycrystalline having hexagonal wurtzite-type crystal structure with strong orientation along (002) plane except 0.025 M, which exhibits a strong orientation in along (100) plane. The bandgap energy, electrical resistivity and thermoelectric power of the films were found to be dependent on the solution concentration. As solution concentration increases, the bandgap energy attenuates from 3.33 to 3.24 eV. The room temperature electrical resistivity was found to be vary in the range 10 2 to 10 −3 Ω cm, whereas thermoelectric power increases from 1×10 −6 to 8×10 −5 V/K. All the films showed n-type conductivity as evidenced from thermoelectric power (TEP) measurement.

Preparation of fluorine-doped tin oxide films at low substrate temperature by an advanced spray pyrolysis technique, and their characterization

Indispensable fluorine-doped tin oxide thin films were prepared on glass substrates by an advanced spray pyrolysis technique at low substrate temperature, with stannic chloride (SnCl4⋅5H2O) and ammonium fluoride (NH4F) as precursors. The films were grown at different substrate temperatures varied in the range of 523–613 K. The influence of the substrate temperature on the structural, morphological, optical and electrical properties of the films has been investigated. XRD studies show that all the films are polycrystalline and have a tetragonal crystal structure. The films deposited at the 613 K substrate temperature exhibit the lowest sheet resistance (17.82 Ω) with optical transmittance of ~75% (at 550 nm). Hall-effect measurements showed that the films are heavily doped degenerate semiconductors with n-type electrical conductivity.

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.

Effect of deposition temperature on spray deposited cadmium oxide films

Abstract Films of cadmium oxide (CdO) were prepared on glass substrates by using spray pyrolysis technique. Films were deposited at different substrate temperatures ranging from 523 K to 723 K. Structural, optical and electrical properties were studied for all samples. X-ray diffraction study showed that films were polycrystalline with preferred orientation along (111), (200), (220) planes with FCC. structure. Optical absorption study reveals that CdO is direct bandgap material and bandgap energy varies from 2.37 eV to 2.25 eV with increase in substrate temperature. The electrical resistivity studies shows resistivity of the film is in the order of 10-4 ohm-cm.

Structural, optical and photoelectrochemical properties of electrodeposited CdSe thin films

Cadmium Selenide thin films have been electrodeposited from an acidic bath using CdSO4 as a cadmium source and SeO2 as a selenium source at pH=3 on to stainless steel and fluorine-tin oxide coated glass substrates. The CdSe films have been characterized by X-ray diffraction, scanning electron microscopy and optical absorption. X-ray diffraction spectra showed that CdSe is polycrystalline with single hexagonal phase. The intensity of the (0 0 2) peak increases remarkably by annealing in nitrogen atmosphere. A microstructural study revealed that the films were uniform and well covered the substrate. Optical absorption studies showed that the bandgap of the CdSe is 1.70 eV. It is observed that the conductivity of the CdSe films increases by annealing in nitrogen atmosphere. The photoelectrochemical activities of CdSe films deposited on stainless steel and fluorine-tin oxide coated glass have been studied by using CdSe/ 1 M NaOH-1 M Na2S-1 MS / C cell configuration and it is found that films deposited on stainless steel give better performance, photoelectrochemical (PEC) studies also reveal that the CdSe has n-type conductivity.

Effect of substrate temperature on transport and optical properties of sprayed Cd1−xZnxS films

Abstract Polycrystalline Cd 1−x Zn x S films are prepared by the spray pyrolysis technique on amorphous substrate, at different substrate temperatures. The dark conductivity and thermoelectric power are measured and applied to calculate the electron density and mobility. The electron density decreases with increase in substrate temperature. However, mobility is higher for the films prepared at 400°C substrate temperature. The variation of electron density and mobility with substrate temperature is explained in terms of crystallanity of the film and chlorine concentration in the films. The optical absorption of the films are studied and revealed that there is not much change in band gap with substrate temperature.

Studies on photoelectrochemical storage celis formed with CdS:Cu electrode

Abstract Copper doped and undoped CdS films are deposited on the stainless steel strips by chemical bath deposition technique and two compartment photoelectrochemical storage cells are formed with these films as photoanodes. The results on photovoltaic energy conversion and storage of these cells are reported and discussed.

Preparation of silver selenide from chemically deposited silver films

Abstract Silver (Ag) films have been converted into silver selenide (Ag 2 Se) films by a chemical method. Thin films of Ag were prepared by chemical deposition using an adsorption-reduction method onto glass substrates and dipped in selenium oxide (SeO 2 ) solution to convert them into Ag 2 Se films. The optical, structural and electrical properties of Ag 2 Se films are reported.