• Saurabh Kumar Pandey

      Articles written in Bulletin of Materials Science

    • Influence of annealing temperature on ZnO thin films grown by dual ion beam sputtering

      Sushil Kumar Pandey Saurabh Kumar Pandey Vishnu Awasthi Ashish Kumar Uday P Deshpande Mukul Gupta Shaibal Mukherjee

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      We have investigated the influence of in situ annealing on the optical, electrical, structural and morphological properties of ZnO thin films prepared on 𝑝-type Si(100) substrates by dual ion beam sputtering deposition (DIBSD) system. X-ray diffraction (XRD) measurements showed that all ZnO films have (002) preferred orientation. Full-width at half-maximum (FWHM) of XRD from the (002) crystal plane was observed to reach to a minimum value of 0.139° from ZnO film, annealed at 600 °C. Photoluminescence (PL) measurements demonstrated sharp near-band-edge emission (NBE) at ∼ 380 nm along with broad deep level emissions (DLEs) at room temperature. Moreover, when the annealing temperature was increased from 400 to 600 °C, the ratio of NBE peak intensity to DLE peak intensity initially increased, however, it reduced at further increase in annealing temperature. In electrical characterization as well, when annealing temperature was increased from 400 to 600 °C, room temperature electron mobility enhanced from 6.534 to 13.326 cm2/V s, and then reduced with subsequent increase in temperature. Therefore, 600 °C annealing temperature produced good-quality ZnO film, suitable for optoelectronic devices fabrication. X-ray photoelectron spectroscopy (XPS) study revealed the presence of oxygen interstitials and vacancies point defects in ZnO film annealed at 400 °C.

    • Bias-dependent photo-detection of dual-ion beam sputtered MgZnO thin films

      Saurabh Kumar Pandey Shaibal Mukherjee

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      The structural, morphological, elemental and electrical properties of MgZnO thin films, grown on p-Si (001) substrates by dual-ion beam sputtering deposition (DIBSD) system at different substrate temperatures were thoroughly investigated. X-ray diffraction (XRD) pattern of MgZnO film exhibited crystalline hexagonal wurtzite structure with the preferred (002) crystal orientation. The full-width at half-maximum of the (002) plane was the narrowest with a value of 0.226° from MgZnO film grown at 400°C. X-ray photoelectron spectroscopy analysis confirmed the substitution of Zn$^{2+}$ by Mg$^{2+}$ in MgZnO thin films and the absence of MgO phase. Correlation between calculated crystallite size, as evaluated from XRD measurements, and room-temperature carrier mobility, as obtained from Hall measurements, was established. Current–voltage characteristics of MgZnO thin films were carried out under the influence of dark and light illumination conditions and corresponding values of photosensitivity were calculated. MgZnO film grown at 100°C exhibited the highest photosensitivity of 1.62. Compared with one of the best-reported values of photosensitivity factor from ZnO-material-based films available in the literature, briefly, $\sim$3.085-fold improved photosensitivity factor at the same bias voltage (2 V) was obtained.

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