Applied Mechanics and Materials Vol. 481

Abstract: In this paper, aluminum induced crystallization (AIC) was studied by examining the effect of using solution derived AlCl₃ catalyst. Such catalyst preparation method offers possibility of low-cost, non-vacuum solution process and allows examination of the role of alumina on the AIC process. The deposited AIC films were examined by using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Raman spectroscopy, X-ray diffraction (XRD) and four probe measurements. It was found that AIC process is highly dependent on annealing temperature and can occur at annealing temperatures above 500°C through Al₂O₃ formation. Based on the presented data, a possible growth model is proposed to clarify AIC mechanism.

Abstract: To solve a common problem existing in most of the present arbitrated quantum signature (AQS) protocols, a new AQS scheme is proposed, in which the security is based on both quantum cryptographic techniques and some ideas in classical cryptography. With message bits intertwined in the proposed scheme, an eavesdropper cannot modify the transmitted message for his own benefit. This scheme provides higher security.

Abstract: Theoretical and practical principles of interaction of light with systems of metallic localized nanoparticles have been outlined and the importance of the electron-optical phonon resonance detuning effect was emphasized to design and develop nanotechnology devices. The demonstration of solar radiation interaction with surface-located gold nanoparticles on rutile was resulted in about 20 times enhancement in energy absorption. This gives possibility to improve different techniques such as energy conversion using optimally structured surfaces.

Abstract: Copper nanoparticles (CuNPs) have been prepared by the reduction of copper chloride in glycerol using hydrazine at ambient conditions. The reduction process takes place under vigorous stirring for 8 h. The formation of CuNPs and size were confirmed by UV/Vis analysis and TEM imaging respectively. The experiment result showed that, 7.062 mM of hydrazine solution and 0.0147 mM of Cu²⁺ solution were needed to synthesize narrow size monodisperseCuNPs.The presence of nanoparticle was found after an induction period of 4 h and further reaction time, complete Cu⁰ state nanoparticle was obtained as deep red wine colour was observed. Stability study of CuNPs showed that the nanoparticles were stable up to 4 days. The particle size of the nanoparticles have been analysed by transmission electron microscopy (TEM) and the average size of CuNPs was in the range 2 to 10 nm.

Abstract: Rapid-melting growth of SiGe stripes on insulator without crystal-seed has been investigated. After rapid-thermal annealing (RTA) of amorphous SiGe stripes (~5 μm) at a temperature between melting-point and solidification-point, SiGe crystals with large lateral sizes (~20 μm) are formed. The Si concentrations in the grains show peaks at the center of the grains and gradually decrease toward the grain boundaries. These phenomena are explained based on the self-organized formation of Si-rich micro-crystals and subsequent Si-segregating lateral-growth during RTA.

Abstract: In this work, we report two methods to fabricate the nanophase-change memory: (1) electron beam lithography (EBL) using the positive resist ZEP-520A followed by phase change material deposition and lift-off processes, (2) EBL using the negative resist hydrogen silsesquioxane (HSQ) followed by reactive ion etching (RIE) after phase change material deposition. For the former method, the optimized exposure dosage is around 40 μC/cm² and the finest nanowire is about 80 nm in width. On the other hand, the latter method shows that the finest nanowire can be as small as about 15 nm in width after RIE process and the optimized exposure dosage is around 2.0 mC/cm². In this case, collapse-preventing pattern becomes necessary for fabrication of such a fine nanowire.

Abstract: Iron oxide nanoparticles were synthesized by employing an ultrasonic homogenizer in conjunction to the co-precipitation of Fe (NO₃)₃·9H₂O, FeCl₂·4H₂O and NaOH. Synchrotron X-ray absorption near edge structure (XANES) spectra could be fitted with the contributions from hematite (α-Fe₂O₃) and, to a lesser extent, metallic Fe. The increase in reagent concentrations increased the Fe fraction which partly explained the change in magnetization of superparamagnetic particles. Nevertheless, the α-Fe₂O₃ composition was increased by using a longer reaction time.

Abstract: Using Transfer Matrix Method (TMM) the Eigen energy of the GaN/AlGaN quantum wire has been evaluated. Peak density results show the confinement and tunneling of electron distribution in quantum wire due to band offset of GaN (wire region) and AlGaN (barrier region). The impact of this band offset results in variation in Eigen energy and is significant in Tunneling phenomenon study to realize the transmission coefficient across the cross-section. Our analysis reveals that for wider wires transmission coefficient reaches to its peak for lower Eigen energy values. Likewise, increase in aluminum mole fraction in AlGaN decreases tunneling effect.

Abstract: In this paper, the effect of post annealing temperature for 5% Cerium doped ZnO thin films have been investigated. Films have been deposited on to the glass substrate using spin coating method. The structural and optical properties of the films were characterized using X-ray diffractometer and UV-spectrophotometer. Transmission of the films was found to be increase with increasing post annealing temperature. Average transmission of all the films was found to be more than 90%. Optical band gap show a minor variation with post annealing temperature. Nanostructures of cerium doped ZnO have been confirmed through AFM.