Yazar "Tombak, A." seçeneğine göre listele

Listeleniyor 1 - 2 / 2
  • [ X ]
    Öğe
    Cu/SnO2 gas sensor fabricated by ultrasonic spray pyrolysis for effective detection of carbon monoxide
    (Elsevier, 2019) Tombak, A.; Ocak, Y. S.; Bayansal, F.
    In this paper, we report results of morphological, structural, optical analysis of ultrasonically sprayed Cu-doped SnO2 thin films and their applications in conductometric gas sensors to detect small traces of CO molecules. Effects of Cu-doping on morphological, structural and optical properties of SnO2 nanostructures were investigated by Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), and UV-Vis. Spectroscopy measurements. Scanning electron microscopy revealed that porosity of the film surfaces is increased with increasing Cu-doping. From the XRD patterns, the size of the crystallites and crystal quality of the films are found to be decreased with Cu-doping. UV-Vis. spectroscopy results presented that the transmittance and bandgap can be manipulated with Cu-doping where both are decreased with Cu-doping. The relation between morphology and structure of the films with CO response properties are discussed properly. The gas response of the films with different Cu-doping has been investigated at different CO concentrations at different operating temperatures. From the sensing measurements, it is found that Cu-doping improves the SnO2 based sensor response to CO gas. Furthermore, the possible sensing mechanism to enlighten the improved gas sensing behavior of the films is proposed.
  • [ X ]
    Öğe
    The novel transparent sputtered p-type CuO thin films and Ag/p-CuO/n-Si Schottky diode applications
    (Elsevier Science Bv, 2015) Tombak, A.; Benhaliliba, M.; Ocak, Y. S.; Kilicoglu, T.
    In the current paper, the physical properties and microelectronic parameters of direct current (DC) sputtered p-type CuO film and diode have been investigated. The film of CuO as oxide and p-type semiconductor is grown onto glass and n-Si substrates by reactive DC sputtering at 250 degrees C. After deposition, a post-annealing procedure is applied at various temperatures in ambient. Through this research, several parameters are determined such structural, optical and electrical magnitudes. The thickness of CuO thin films goes from 122 to 254 nm. A (111)-oriented cubic crystal structure is revealed by X-ray analysis. The grain size is roughly depending on the post-annealing temperature, it increases with temperature within the 144-285 nm range. The transmittance reaches 80% simultaneously in visible and infrared bands. The optical band gap is varied between 1.99 and 2.52 eV as a result of annealing temperature while the resistivity and the charge carrier mobility decrease with an increase in temperature from 135 to 14 Omega cm and 0.92 to 0.06 cm(2)/Vs, respectively. The surface of samples is homogenous, bright dots are visible when temperature reaches the highest value. As a diode, Ag/CuO/n-Si exhibits a non-ideal behavior and the ideality factor is about 3.5. By Norde method, the barrier height and the series resistance are extracted and found to be 0.96 V and 86.6 Omega respectively. (C) 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).