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Reddy V.R.,Sri Venkateswara University | Reddy M.S.P.,Sri Venkateswara University | Kumar A.A.,Yv University | Choi C.-J.,Chonbuk National University
Thin Solid Films | Year: 2012

In the present work, thin film of polyvinyl alcohol (PVA) is fabricated on n-type InP substrate as an interfacial layer for electronic modification of Au/n-InP Schottky contact. The electrical characteristics of Au/PVA/n-InP Schottky diode are determined at annealing temperature in the range of 100-300°C by current-voltage (I-V) and capacitance-voltage (C-V) methods. The Schottky barrier height and ideality factor (n) values of the as-deposited Au/PVA/n-InP diode are obtained at room temperature as 0.66 eV (I-V), 0.82 eV (C-V) and 1.32, respectively. Upon annealing at 200°C in nitrogen atmosphere for 1 min, the barrier height value increases to 0.81 eV (I-V), 0.99 eV (C-V) and ideality factor decreases to 1.18. When the contact is annealed at 300°C, the barrier height value decreases to 0.77 eV (I-V), 0.96 eV (C-V) and ideality factor increases to 1.22. It is observed that the interfacial layer of PVA increases the barrier height by the influence of the space charge region of the Au/n-InP Schottky junction. The discrepancy between Schottky barrier heights calculated from I-V and C-V measurements is also explained. Further, Cheung's functions are used to extract the series resistance of Au/PVA/n-InP Schottky diode. The interface state density as determined by Terman's method is found to be 1.04 × 10 12 and 0.59 × 10 12 cm - 2 eV - 1 for the as-deposited and 200°C annealed Au/PVA/n-InP Schottky diodes. Finally, it is seen that the Schottky diode parameters changed with increase in the annealing temperature. © 2012 Elsevier B.V.

Siva Pratap Reddy M.,Sri Venkateswara University | Ashok Kumar A.,Yv University | Rajagopal Reddy V.,Sri Venkateswara University
Thin Solid Films | Year: 2011

The electrical transport properties of Ni/Pd/n-GaN Schottky barrier diodes (SBDs) have been investigated in the wide temperature range of 100-425 K. An abnormal decrease in the experimental barrier height (φb) and an increase in the ideality factor (n) with a decrease in the temperature have been observed. The observed variation in φbo and n is attributed to the spatial barrier inhomogeneities in Schottky barrier height by assuming a Gaussian distribution (GD) of barrier heights (BHs) at 100-175 K and 175-425 K. The temperature-dependent current-voltage characteristics of the SBDs has shown a double Gaussian distribution giving mean barrier heights of 0.65 eV and 1.21 eV and standard deviations of 0.085 and 0.159 V, respectively. A modified ln (Io/T2)-q2σo 2/2k2T2 versus 103/T plot for the two temperature regions gives φbō and A* as 0.713 eV and 13.56 A cm- 2 K- 2, and 1.34 eV and 28.645 A cm- 2 K- 2 respectively. Such temperature dependence of modified Richardson plot and electrical parameters of Ni/Pd/n-GaN SBD can be explained based on the thermionic emission theory with double GD of BHs due to the barrier height inhomogeneities at the metal/semiconductor interface. The themionic field emission is considered as the phenomena responsible for the excess currents observed in both forward and reverse direction of Schottky barriers. © 2011 Elsevier B.V. All rights reserved.

Naresh Kumar Reddy B.,Koneru Lakshmaiah College of Engineering | Naga Raju C.,Yv University | Sridhar K.,Yv University
International Journal of Applied Engineering Research | Year: 2014

In Automated Teller Machines (ATMs) fraud became more widespread. Computation of biometric offers an effective approach for ATM customer's identification/verification with unique physical/behavioural characteristics. In this paper a new framework is designed to enhance level of security at ATM's by doing customer verification with palm print recognition. First, method extracts low frequency palm print features by applying 2D DCT (Discrete Cosine Transform).Features of training and test sets are matched using Euclidian distance. Experimental results shows promising performance of proposed method with high level of recognition rate against standard and local databases namely PolyU Palm print and LBRCE_PALM_DB. © Research India Publications.

Prathima B.,Sv University | Subba Rao Y.,Sv University | Adinarayana Reddy S.,Yv University | Reddy Y.P.,Sri Padhmavati Mahila Visva Vidyalayam Womens University | Varada Reddy A.,Sv University
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2010

Benzyloxybenzaldehyde-4-phenyl-3-thiosemicarbazone ligand (L) has been synthesized from benzyloxybenzaldehyde and 4-phenyl-3-thiosemicarbazide. Complexes of this ligand with chlorides of Cu(II) and Ni(II) have been prepared. The structure of the ligand (L) is proposed based on elemental analysis, IR and 1H NMR spectra. Its complexes with Cu(II) and Ni(II) ions are characterized from the studies of electronic as well as EPR spectra. On the basis of electronic and EPR studies, rhombically distorted octahedral structure has been proposed for Cu(II) complex while the Ni(II) complex has been found to acquire an octahedral structure. The ligand and their metal complexes have been tested in vitro for their biological effects. Their antibacterial activities against Gram-negative bacteria (Escherichia coli and Klebsiella pneumoniae) and Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis) have been investigated. The prepared metal complexes exhibit higher antibacterial activities than the parent ligand. The in vitro antioxidant activity of free ligand and its metal(II) complexes have also been investigated and the results however reveal that the ligand exhibits greater antioxidant activity than its complexes. © 2010 Elsevier B.V.

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