Document Type : Research Paper
Authors
1 electronic and communication engineering/ electrical engineering/The University of Technology, Iraq
2 Department of Electrical Engineering, University of Technology, Baghdad, Iraq
3 Nanotechnology and Advanced Materials Research, College of Engineering, University of Kufa, Najaf, Iraq
Abstract
Hydrothermal preparations have been made form vanadium oxygen systems V2O5 and VO2 NPs prototype to design photodetectors. In comparison, the films' polycrystalline structure can be seen in analysis of x-ray diffraction (XRD) pattern, which has 7 and 14 peaks with crystallite sizes = 19.59 for V2O5 and, crystallite sizes = 12.92 nm, for VO2. The grains had large, neatly separated conical columnar growth combined grains throughout the surface, with some of the columnar grains coalescing in a few spots, according to the analysis from atomic force microscopy (AFM). It is revealed that the average size of particle of V2O5 =29.58 nm and for VO2 = 16 nm, with rms roughness of 6.8 nm and 21.3 nm respectively. Also, the optical energy gap of V2O5 = 2.6 eV, whereas energy gap of VO2 = 1.36 eV. In addition, it was discovered that the reflectance increased in the visible and infrared regions to register 0.09 and 0.07 respectively. The maximum values of the refractive indices for V2O5 and VO2 were 2.6 and 1.9, respectively. Two types of hetero-junction photo-detectors Ag/VO2/PSi/n-Si/Ag and Ag/V2O5/PSi/n-Si/Ag have been fabricated and characterized. The proposed results of Ag/ V2O5 /PSi/n-Si/Ag heterojunction Photo-detector at different concentrations from PMMA: Acetone responsivity was 0.7A/W at 850nm and, the remarkable detectivity = 4.1 x 1012 (1/W) .cm. Hz0.5 , while, highest values of the detectivity in Ag/VO2/PSi/n-Si/Ag = 3.3 x 1012 (1/W) .cm.Hz0.5 . at wavelength equal and greater than 850 nm
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