Annealing and light effect on optical and electrical properties of ZnS thin films grown with the SILAR method

Zinc sulphide (ZnS) thin films were grown on glass substrates by the Successive Ionic Layer Adsorption and Reaction (SILAR) technique at room temperature and ambient pressure. Surface morphologies of grown films were characterized using scanning electron microscopy (SEM). The crystal structure and crystal size of the thin films were characterized by the X-ray diffraction (XRD) method and found that the films exhibit polycrystalline characterization. The optical absorption measurements were done as a function of the temperature at 10–320 K temperature range. Using absorption measurements, the band gap energies were calculated at 10 and 320 K, as 3.83 and 3.72 eV, respectively. The annealing temperature effect on optical band gap and the light effect on the electrical properties of ZnS thin films were investigated and it was found that the current increased with increasing light intensity. The annealed films were found have more resistance than the as-grown film.     

Analysis and Design of Low-Cost Bit-Serial Architectures for Motion Estimation in H.264/AVC

Variable block-size motion estimation (VBSME) process occupies a major part of computation of an H.264 encoder, which is usually accelerated by bit-parallel hardware architectures with large I/O bit width to meet real-time constrains. However, such kind of architectures increase the area overhead and pin count, and therefore will not be suitable for area-constrained electronic consumer designs such as small portable multimedia devices. This paper addresses this problem by proposing two area efficient least significant bit (LSB) bit-serial architectures with small pin numbers. Both designs take advantage of data reusing technique in different ways for sum of absolute differences (SAD) computation and reading reference pixels, leading to a considerable reduction of memory bandwidth. The first architecture propagates the partial SAD and sum results and broadcasts the reference pixel rows whereas the second design reuse the SAD of small blocks and has a reconfigurable reference buffer leading to a better memory bandwidth when using hardware parallelism. The proposed designs benefit from several optimization techniques including an efficient serial absolute difference architecture, word length reduction by parallelism, bit truncation, mode filtering, and macroblock (MB) level subsampling, which significantly enhance their performances in terms of silicon area, throughput, latency, and power consumption. The first and second designs can support full search VBSME of 720?×?480 video with 30 frames per second (fps), two reference frames, and [?16, 15] search range at a clock frequency of 414 MHz with 29.28 k and 31.5 k gates, respectively.     

Review study of electrochemical impedance spectroscopy and equivalent electrical circuits of conducting polymers on carbon surfaces

Electrochemical impedance spectroscopy (EIS) is an experimental method for characterizing electrochemical systems. This method measures the impedance of the concerned electrochemical system over a range of frequencies, and therefore the frequency response of the system is determined, including the energy storage and dissipation properties. The aim of this article is to review articles focusing on electrochemical impedance spectroscopic studies and equivalent electrical circuits of conducting polymers, such as polypyrrole, polycarbazole, polyaniline, polythiophene and their derivatives, on carbon surfaces. First, the conducting polymers are introduced. Second, the electrochemical impedance spectroscopic method is explained. Third, the results of EIS applications using equivalent electrical circuits for conducting polymers taken from the literature are reviewed.     

Synthesis of 9‐(4‐nitrophenylsulfonyl)‐9H‐carbazole: Comparison of an impedance study of poly[9‐(4‐nitrophenylsulfonyl)‐9H‐carbazole] on gold and carbon fiber microelectrodes

In this study, 9‐(4‐nitrophenylsulfonyl)‐9H‐carbazole (NPhSCz) monomer was chemically synthesized. The monomer characterization was performed by Fourier transform infrared spectroscopy, ¹H‐NMR, and melting point analysis. Two different electropolymerizations of NPhSCz were studied on a gold microelectrode (Au electrode) and carbon fiber microelectrodes (CFMEs) in a 0.1M sodium perchlorate (NaClO₄)/acetonitrile solution. The electropolymerization experiments were done from 1 to 4 mM. The characterizations of two different modified electrodes of poly[9‐(4‐nitrophenylsulfonyl)‐9H‐carbazole] [poly(NPhSCz)] were performed by various techniques, including cyclic voltammetry, scanning electron microscopy–energy‐dispersive X‐ray analysis, and electrochemical impedance spectroscopy (EIS). The effects of the initial monomer concentrations (1, 2, 3, and 4 mM) were examined by EIS. The capacitive behaviors of the modified electrodes were defined via Nyquist, Bode magnitude, Bode phase, and admittance plots. The variation of the low‐frequency capacitance (C_LF) and double‐layer capacitance (C_dl) values are presented at different initial monomer concentrations. Poly(NPhSCz)/CFME was more capacitive (C_LF = 6.66 F/cm² and C_dl ≈ 28 mF) than the Au electrode (C_LF = 6.53 F/cm² and C_dl ≈ 20 mF). An equivalent circuit model of R[QR(CR)(RW)](CR), (R: Current, Q: Constant phase element, C: Double layer capacitance, W: Warburg impedance), was used to fit the theoretical and experimental data. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011