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CONTENTS
Volume 2, Number 4, December 2014
 

Abstract
Indium-nitrogen co-doped zinc oxide thin films (INZO) were prepared on glass substrates in the atmosphere by ultrasonic spray pyrolysis. The aqueous solution of zinc acetate, ammonium acetate and different indium sources: indium (III) chloride and indium (III) nitrate were used as the precursors. After film deposition, different anneal temperature treatment as 350, 450, 550oC were applied. Electrical properties as concentration and mobility were characterized by Hall measurement. The surface morphology and crystalline quality were characterized by SEM and XRD. With the activation energy analysis for both films, the concentration variation of the films at different heat treatment temperature was realized. Donors correspond to zinc related states dominate the conduction mechanism for these INZO films after 550oC high temperature heat treatment process.

Key Words
indium-nitrogen co-doped zinc oxide; anneal; resistivity

Address
Wen-How Lan, Yue-Lin Li, Yu-Chieh Chung, Yi-Chun Chou, Yi-Da Wu: Department of Electrical Engineering, National University of Kaohsiung, Nan-Tzu 811, Kaohsiung, Taiwan
Cheng-Chang Yu, Kai-Feng Huang: Department of Electrophysics, National Chiao Tung University, Hsinchu 300, Taiwan
Lung-Chien Chen: Department of Electro-optical Engineering, National Taipei University of Technology, Taipei 106, Taiwan

Abstract
Magnetite nanoparticles (MNPs) of different sizes were synthesized by solvothermal process maintaining their stoichiometric composition and unique structural phase. Utilizing hydrated ferric (III) chloride as unique iron precursor, it was possible to synthesize sub-micrometric magnetite clusters of sizes in between 208 and 381 nm in controlled manner by controlling the concentration of sodium acetate in the reaction mixture. The sub-micrometer size nanoclusters consist of nanometric primary particles of 19 - 26.3 nm average size. The concentration of sodium acetate in reaction solution seen to control the final size of primary MNPs, and hence the size of sub-micrometric magnetite nanoclusters. All the samples revealed their superparamagnetic behavior with saturation magnetization (Ms) values in between 74.3 and 77.4 emu/g. Ms. The coercivity of the nanoclusters depends both on the size of the primary particles and impurity present in them. The mechanisms of formation and size control of the MNPs have been discussed.

Key Words
magnetite nanoclusters; solvothermal synthesis; size control; magnetic properties

Address
Sergio I. Uribe Madrid, Umapada Pal: Instituto de Física, Benemérita Universidad Autónoma de Puebla, Apdo. Postal J-48, Puebla, Pue. 72570, Mexico
Felix Sanchez-De Jesus: Area Academica de Ciencias de la Tierra y Materiales, Universidad Autónoma del Estado de Hidalgo, Carr. Pachuca-Tulancingo Km. 4.5, 42184 Pachuca, Hidalgo, Mexico


Abstract
Carbon nanotubes have exceptional mechanical, thermal and electrical properties, and are considered for high performance structural and multifunctional composites. In the present study, the natural frequencies of aligned single walled carbon nanotube (CNT) reinforced composite beams are obtained using shear deformable composite beam theories. The Ritz method with algebraic polynomial displacement functions is used to solve the free vibration problem of composite beams. The Mori-Tanaka method is applied to find the composite beam mechanical properties. The continuity conditions are satisfied among the layers by modifying the displacement field. Results are found for different CNT diameters, length to thickness ratio of the composite beam and different boundary conditions. It is found that the use of smaller CNT diameter in the reinforcement element gives higher fundamental frequency for the composite beam.

Key Words
carbon nanotubes; nano composites; mechanical properties; vibration; laminate theory

Address
Metin Aydogdu: Department of Mechanical Engineering, Trakya University, 22030, Edirne, Turkey

Abstract
The self-assembled strain-induced sub-micrometric islands and nanostructures are grown from In-As-Sb-P quaternary liquid phase on InAs (100) substrates in Stranski-Krastanow growth mode. Two samples are under consideration. The first sample consists of unencapsulated islands and lens-shape quantum dots (QDs) grown from expressly inhomogeneous liquid phase. The second sample is an n-InAs/p-InAsSbP heterostructure with QDs embedded in the p-n junction interface. The morphology, size and shape of the structures are investigated by high-resolution scanning electron (SEM) and transmission electron (TEM) microscopy. It is shown that islands, as they decrease in size, undergo shape transitions. Particularly, as the volume decreases, the following succession of shape transitions are detected: sub-micrometric truncated pyramid, {111} facetted pyramid, {111} and partially {105} facetted pyramid, completely unfacetted \"pre-pyramid\", hemisphere, lens-shaped QD, which then evolves again to nano-pyramid. A critical size of 5+-2 nm for the shape transformation of InAsSbP-based lens-shaped QD to nano-pyramid is experimentally measured and theoretically evaluated.

Key Words
strain-induced; pyramids; quantum dots; shape transition; III-V semiconductors

Address
Karen M. Gambaryan: Engineering Research Center for Semiconductor Integrated Technology, Institute of Semiconductors, Chinese Academy of Science, Beijing 100083, P.R. China; Department of Physics of Semiconductors and Microelectronics, Yerevan State University,
1 Alex Manoogian St., Yerevan 0025, Armenia
Vladimir M. Aroutiounian: Department of Physics of Semiconductors and Microelectronics, Yerevan State University, 1 Alex Manoogian St., Yerevan 0025, Armenia
Arpine K. Simonyan: Department of Physics of Semiconductors and Microelectronics, Yerevan State University,
1 Alex Manoogian St., Yerevan 0025, Armenia
Yuanfei Ai: Engineering Research Center for Semiconductor Integrated Technology, Institute of Semiconductors,
Chinese Academy of Science, Beijing 100083, P.R. China; Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of
China, Chengdu 610054, P.R. China
Eric Ashalley: Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of
China, Chengdu 610054, P.R. China
Zhiming M. Wang: Engineering Research Center for Semiconductor Integrated Technology, Institute of Semiconductors, Chinese Academy of Science, Beijing 100083, P.R. China; Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of
China, Chengdu 610054, P.R. China

Abstract
A simple preparation method on creating superhydrophobic surface using non-aligned carbon nanotubes (CNTs) was demonstrated. Superhydrophobic CNT thin films were prepared by doping a sonicated mixture of CNTs and chloroform onto a glass slide. Water contact angles of the CNT thin films were measured using a contact angle goniometer. The thin films were characterized using laser microscope and scanning electron microscope. Experimental results revealed that the highest average contact angle of 162+-2o was achieved when the films\' thickness was 1.628 µm. The superhydrophobic surface was stable as the contact angle only receded from 162+-2 to 157+-2o after 10 min under normal atmospheric condition.

Key Words
carbon nanotubes; non-aligned, superhydrophobic; thin film; characterization

Address
Yee-Miin Goh, Kok Deng Han, Lling-Lling Tan and Siang-Piao Chai: Multidisciplinary Platform of Advanced Engineering, Chemical Engineering Discipline, School of Engineering, Monash University, Jalan Lagoon Selatan, 46150 Bandar Sunway, Selangor, Malaysia


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