• S R Bhattacharyya

      Articles written in Bulletin of Materials Science

    • Cone formation on Ag surface bombarded by Ar at oblique incidence

      S R Bhattacharyya T K Chini D Basu

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      Sputter-induced topographical modifications of a silver surface bombarded by mass-analysed ions of 30 keV40Ar+ obtained from an electromagnetic isotope separator incident at an angle of 58° was studied. Analysis of the silver surface by scanning electron microscopy showed that most of the bombarded area was covered with features similar to corrugated terrace steps, sharp and fine cones, and pyramids. The underlying mechanism for formation of such features is discussed. The method of formation of such sharp cones produced by ion bombardment will increasingly find applications in the formation of fine tips required in scanning probe and field emission microscopy.

    • Fabrication and characterization of transparent nanocrystalline ZnO thin film transistors by a sol–gel technique

      S R BHATTACHARYYA R N GAYEN

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      A nanocrystalline zinc oxide (ZnO) thin film-based metal–insulator–semiconductor thin film transistor (MISTFT) was fabricated by a facile sol–gel technique onto silicon di-oxide/indium tin oxide-coated glass substrates. Themicrostructural study of the ZnO thin films indicated uniform crystalline growth with typical (002) X-ray diffraction peaks for h-ZnO with a wurtzite structure. The optical transmittance of the ZnO thin films was >80% in the visible region of theelectromagnetic spectrum. The field effect transistor (FET) aluminium top contacts were fabricated using suitable shadow masking. The transfer characteristics of a typical ZnO MIS FET revealed nonlinearity in a linear plot. From the slope and crossover, we obtained a first estimate of field effect mobility ($\mu$) and threshold voltage ($V_T$) of 0.13 cm$^2$ V$^{−1}$ s$^{−1}$ and1.03 eV, respectively. The ZnO TFT operated in enhanced mode with n-channel characteristics and the drain current on–off ratio was 105. The deposition parameter needs to be optimized to obtain TFTs with a higher modulation ratio and larger field-effect mobility.

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