http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/761 Wed, 19 Jun 2013 14:16:11 GMT 2013-06-19T14:16:11Z http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/792 Optical and electrical properties of co-sputtered amorphous transparent conducting zinc indium tin oxide thin films Jayaraj, M K Highly conductive and transparent thin films of amorphous zinc indium tin oxide are prepared at room temperature by co-sputtering of zinc 10 oxide and indium tin oxide. Cationic contents in the films are varied by adjusting the power to the sputtering targets. Optical transmission study of 11 films showed an average transmission greater than 85% across the visible region. Maximum conductivity of 6×102 S cm−1 is obtained for Zn/In/ 12 Sn atomic ratio 0.4/0.4/0.2 in the film. Hall mobility strongly depends on carrier concentration and maximum mobility obtained is 18 cm2 V−1 s−1 13 at a carrier concentration of 2.1×1020 cm−3. Optical band gap of films varied from 3.44 eV to 3 eV with the increase of zinc content in the film 14 while the refractive index of the films at 600 nm is about 2.0. Fri, 19 Oct 2007 00:00:00 GMT http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/792 2007-10-19T00:00:00Z http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/791 Transparent p-AgCoO2/n-ZnO diode heterojunction fabricated by pulsed laser deposition Jayaraj, M K Transparent diode heterojunction on ITO coated glass substrates was fabricated using p-type AgCoO2 and n-type ZnO films by pulsed laser deposition (PLD). The PLD of AgCoO2 thin films was carried out using the pelletized sintered target of AgCoO2 powder, which was synthesized in-house by the hydrothermal process. The band gap of these thin films was found to be ~3.89 eV and they had transmission of~55% in the visible spectral region. Although Hall measurements could only indicate mixed carrier type conduction but thermoelectric power measurements of Seebeck coefficient confirmed the p-type conductivity of the grown AgCoO2 films. The PLD grown ZnO films showed a band gap of ~3.28 eV, an average optical transmission of ~85% and n-type carrier density of~4.6×1019 cm− 3. The junction between p-AgCoO2 and n-ZnO was found to be rectifying. The ratio of forward current to the reverse current was about 7 at 1.5 V. The diode ideality factor was much greater than 2. Thu, 01 Mar 2007 00:00:00 GMT http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/791 2007-03-01T00:00:00Z http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/790 Synthesis of ZnO nanoparticles by hydrothermal method Jayaraj, M K Stable, OH free zinc oxide (ZnO) nanoparticles were synthesized by hydrothermal method by varying the growth temperature and concentration of the precursors. The formation of ZnO nanoparticles were confirmed by x-ray diffraction (XRD), transmission electron microscopy (TEM) and selected area electron diffraction (SAED) studies. The average particle size have been found to be about 7-24 nm and the compositional analysis is done with inductively coupled plasma atomic emission spectroscopy (ICP-AES). Diffuse reflectance spectroscopy (DRS) results shows that the band gap of ZnO nanoparticles is blue shifted with decrease in particle size. Photoluminescence properties of ZnO nanoparticles at room temperature were studied and the green photoluminescent emission from ZnO nanoparticles can originate from the oxygen vacancy or ZnO interstitial related defects. Mon, 01 Jan 2007 00:00:00 GMT http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/790 2007-01-01T00:00:00Z http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/789 Growth of zinc oxide thin films for optoelectronic application by pulsed laser deposition Jayaraj, M K Zinc oxide (ZnO) thin films were deposited on quartz, silicon, and polymer substrates by pulsed laser deposition (PLD) technique at different oxygen partial pressures (0.007 mbar to 0.003 mbar). Polycrystalline ZnO films were obtained at room temperature when the oxygen pressure was between 0.003 mbar and .007 mbar, above and below this pressure the films were amorphous as indicated by the X-ray diffraction (XRD). ZnO films were deposited on Al2O3 (0001) at different substrate temperatures varying from 400oC to 600oC and full width half maximum (FWHM) of XRD peak is observed to decrease as substrate temperature increases. The optical band gaps of these films were nearly 3.3 eV. A cylindrical Langmuir probe is used for the investigation of plasma plume arising from the ZnO target. The spatial and temporal variations in electron density and electron temperature are studied. Optical emission spectroscopy is used to identify the different ionic species in the plume. Strong emission lines of neutral Zn, Zn+ and neutral oxygen are observed. No electronically excited O+ cations are identified, which is in agreement with previous studies of ZnO plasma plume. Sun, 01 Jan 2006 00:00:00 GMT http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/789 2006-01-01T00:00:00Z