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Kosach, N. I., V. B. Bolshakov, I. T. Bohdanov i Y. O. Suchikova. "Statistical evaluation of morphological parameters of porous nanostructures on the synthesized indium phosphide surface". Bulletin of the Karaganda University. "Physics" Series 103, nr 3 (30.09.2021): 83–92. http://dx.doi.org/10.31489/2021ph3/83-92.
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A constructive method for estimating the surface morphology of nanostructured semiconductors, which consists in determining the main statistical characteristics of the aggregate structure of nanoscale objects on their synthesized surface is presented. In terms of the indium phosphide semiconductor with a synthesized porous layer on its surface, it is shown that the evaluation of the main statistical characteristics allows a deeper understanding of the kinetics of the pore formation process during typical electrochemical treatment of the crystal. The determination of the main statistical metrologically based characteristics (indicators of the distribution center, variation, and shape of the distribution) allows us to understand in more detail view the processes occurring during electrochemical processing of crystals. In the long run, this will make it possible to create nanostructures with predetermined properties, which will become the basis for the industrial production of high-quality nanostructured semiconductors.
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Li, Jing, Wenhua Bi, Wooseok Ki, Xiaoying Huang i Srihari Reddy. "Nanostructured Crystals: Unique Hybrid Semiconductors Exhibiting Nearly Zero and Tunable Uniaxial Thermal Expansion Behavior". Journal of the American Chemical Society 129, nr 46 (listopad 2007): 14140–41. http://dx.doi.org/10.1021/ja075901n.
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Chen, Jihua. "Advanced Electron Microscopy of Nanophased Synthetic Polymers and Soft Complexes for Energy and Medicine Applications". Nanomaterials 11, nr 9 (15.09.2021): 2405. http://dx.doi.org/10.3390/nano11092405.
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After decades of developments, electron microscopy has become a powerful and irreplaceable tool in understanding the ionic, electrical, mechanical, chemical, and other functional performances of next-generation polymers and soft complexes. The recent progress in electron microscopy of nanostructured polymers and soft assemblies is important for applications in many different fields, including, but not limited to, mesoporous and nanoporous materials, absorbents, membranes, solid electrolytes, battery electrodes, ion- and electron-transporting materials, organic semiconductors, soft robotics, optoelectronic devices, biomass, soft magnetic materials, and pharmaceutical drug design. For synthetic polymers and soft complexes, there are four main characteristics that differentiate them from their inorganic or biomacromolecular counterparts in electron microscopy studies: (1) lower contrast, (2) abundance of light elements, (3) polydispersity or nanomorphological variations, and (4) large changes induced by electron beams. Since 2011, the Center for Nanophase Materials Sciences (CNMS) at Oak Ridge National Laboratory has been working with numerous facility users on nanostructured polymer composites, block copolymers, polymer brushes, conjugated molecules, organic–inorganic hybrid nanomaterials, organic–inorganic interfaces, organic crystals, and other soft complexes. This review crystalizes some of the essential challenges, successes, failures, and techniques during the process in the past ten years. It also presents some outlooks and future expectations on the basis of these works at the intersection of electron microscopy, soft matter, and artificial intelligence. Machine learning is expected to automate and facilitate image processing and information extraction of polymer and soft hybrid nanostructures in aspects such as dose-controlled imaging and structure analysis.
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Wang, Z. L. "Energy-filtered high-resolution Electron Microscopy of nanostructured materials". Proceedings, annual meeting, Electron Microscopy Society of America 53 (13.08.1995): 176–77. http://dx.doi.org/10.1017/s0424820100137252.
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The interaction between an incident electron and the atoms in condensed matter results in various inelastic scattering processes. Thermal diffuse scattering or phonon scattering is the result of atomic vibrations in crystals. This process does not introduce any significant energy-loss (< 0.1 eV) but produces large momentum transfer. Valence-loss (or plasmon for metals and semiconductors) excitation, which characterizes the transitions of electrons from the valence band to the conduction band, involves an energyloss in the range of 1 -50 e V. Atomic inner-shell ionization is excited by the energy transfer of the incident electron, resulting in an ejected electron from the deep-core states. Continuous energy-loss spectra can also be generated by an electron which penetrates into the specimen and undergoes collisions with the atoms in it, resulting in Bremsstrahlung and leading to emission of x-rays with continuous energy. The electron Compton scattering refers to the collision of the incident electron with an electron belonging to the specimen. In an electron energy-loss spectrum (EELS), the zero-loss peak is composed of elastically and thermal diffusely scattered electrons. The low-loss region is dominated by valence-excitations.
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Shen, Shaohua, i Samuel S. Mao. "Nanostructure designs for effective solar-to-hydrogen conversion". Nanophotonics 1, nr 1 (1.07.2012): 31–50. http://dx.doi.org/10.1515/nanoph-2012-0010.
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AbstractConversion of energy from photons in sunlight to hydrogen through solar splitting of water is an important technology. The rising significance of producing hydrogen from solar light via water splitting has motivated a surge of developing semiconductor solar-active nanostructures as photocatalysts and photoelectrodes. Traditional strategies have been developed to enhance solar light absorption (e.g., ion doping, solid solution, narrow-band-gap semiconductor or dye sensitization) and improve charge separation/transport to prompt surface reaction kinetics (e.g., semiconductor combination, co-catalyst loading, nanostructure design) for better utilizing solar energy. However, the solar-to-hydrogen efficiency is still limited. This article provides an overview of recently demonstrated novel concepts of nanostructure designs for efficient solar hydrogen conversion, which include surface engineering, novel nanostructured heterojunctions, and photonic crystals. Those first results outlined in the main text encouragingly point out the prominence and promise of these new concepts principled for designing high-efficiency electronic and photonic nanostructures that could serve for sustainable solar hydrogen production.
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Rud, Vasily, Doulbay Melebaev, Viktor Krasnoshchekov, Ilya Ilyin, Eugeny Terukov, Maksim Diuldin, Alexey Andreev, Maral Shamuhammedowa i Vadim Davydov. "Photosensitivity of Nanostructured Schottky Barriers Based on GaP for Solar Energy Applications". Energies 16, nr 5 (28.02.2023): 2319. http://dx.doi.org/10.3390/en16052319.
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This work investigates the surface-barrier photoelectric properties of Au-palladium-n-GaP structures. Research into the visible spectrum region, under the action of both linearly polarized and natural radiation, provides us with new information about the height of the barrier, the interface m-s section, and the GaP band structure. SBs based on GaP (p- and n-type) are helpful for researchers in developing advantageous structures for creating various photovoltaic devices—photodetectors for fiber-optic control of energy systems or possible structures for solar energy. Despite many years of research, issues concerning the band structure of semiconductors based on the phenomenon of photoelectroactive absorption in such surface-barrier structures’ m-s remain urgent in the creation of new high-performance devices. Such structures may also be interesting for creating solar energy systems. They create a thin insulating dielectric layer (usually an oxide layer) in solar cells on SBs between the m and the semiconductor substrate. The advantage of solar cells based on m dielectric semiconductor structures is the strong electric field near the surface of the semiconductor that usually has a direction favoring the collection of carriers created by short-wavelength light. Diffusion of impurities usually results in crystal defects in the active region. There are no such defects in the studied elements. This is also the difference between solar cells on m dielectric structures and elements with diffusion in p-n junctions. We studied the PS of Au-Pd-n-GaP nanostructures to determine the height of the potential barrier qφBo and obtained accurate data on the zone structure of the n-GaP. The PS of nanostructured Au-Pd-n-GaP structures was studied in the visible region of the spectrum. Essential information about the semiconductor’s potential barrier parameters and band structure was obtained. The intermediate Pd nanolayer between Au and GaP has specific effects on the Au-Pd-n-GaP nanostructure, which are of considerable practical and scientific significance for future needs.
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Al-Ahmed, Amir, Bello Mukhtar, Safdar Hossain, S. M. Javaid Zaidi i S. U. Rahman. "Application of Titanium Dioxide (TiO2) Based Photocatalytic Nanomaterials in Solar and Hydrogen Energy: A Short Review". Materials Science Forum 712 (luty 2012): 25–47. http://dx.doi.org/10.4028/www.scientific.net/msf.712.25.
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Tremendous amount of research work is going on Titanium dioxide (TiO2) based materials. These materials have many useful applications in our scientific and daily life and it ranges from photovoltaics to photocatalysis to photo-electrochromics, sensors etc.. All these applications can be divided into two broad categories such as environmental (photocatalysis and sensing) and energy (photovoltaics, water splitting, photo-/electrochromics, and hydrogen storage). Synthesis of TiO2nanoparticles with specific size and structural phase is crucial, for solar sell application. Monodispersed spherical colloids with minimum size variation (5% or less) is essential for the fabrication of photonic crystals. When sensitized with organic dyes or inorganic narrow band gap semiconductors, TiO2can absorb light into the visible light region and convert solar energy into electrical energy for solar cell applications. TiO2nanomaterials also have been widely studied for water splitting and hydrogen production due to their suitable electronic band structure given the redox potential of water. Again nanostructured TiO2has extensively been studied for hydrogen storage with good storage capacity and easy releasing procedure. All these issues and related finding will be discussed in this review.
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Gnawali, Guna Nidha, Shankar P. Shrestha, Khem N. Poudyal, Indra B. Karki i Ishwar Koirala. "Study on the effect of growth-time and seed-layers of Zinc Oxide nanostructured thin film prepared by the hydrothermal method for liquefied petroleum gas sensor application". BIBECHANA 16 (22.11.2018): 145–53. http://dx.doi.org/10.3126/bibechana.v16i0.21557.
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Gas sensors are devices that can convert the concentration of an analytic gas into an electronic signal. Zinc oxide (ZnO) is an important n-type metal oxide semiconductor which has been utilized as gas sensor for several decades. In this work, ZnO nanostructured films were synthesized by a hydrothermal route from ZnO seeds and used as a liquefied petroleum gas (LPG) sensor. At first ZnO seed layers were deposited on glass substrates by using spin coating method, then ZnO nanostructured were grown on these substrates by using hydrothermal growth method for different time duration. The effect of growth time and seed layers of ZnO nanostructured on its structural, optical, and electrical properties was studied. These nanostructures were characterized by X-ray diffraction, scanning electron microscopy, optical spectroscopy, and four probes sheet resistance measurement unit. The sensing performances of the synthetic ZnO nanostructures were investigated for LPG.XRD showed that all the ZnO nanostructures were hexagonal crystal structure with preferential orientation. SEM reviled that the size of nanostructure increased with increase in growth time. Band gap and sheet resistance for ZnO nanostructured thin film decreased with increase in growth time. ZnO nanostructured thin film showed high sensitivity towards LPG gas. The sensitivity of the film is observed to increase with increase in no of seed layers as well as growth time. The dependence of the LPG sensing properties on the different growth time of ZnO nanostructured was investigated. The sensing performances of the film were investigated by measured change in sheet resistance under expose to LPG gas. BIBECHANA 16 (2019) 145-153
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Suchikova, Y. O., S. S. Kovachov, G. O. Shishkin, D. O. Pimenov, A. S. Lazarenko, V. V. Bondarenko i I. T. Bogdanov. "Functional model for the synthesis of nanostructures of the given quality level". Archives of Materials Science and Engineering 2, nr 107 (1.02.2021): 72–84. http://dx.doi.org/10.5604/01.3001.0015.0244.
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Purpose: The aim of this paper is to develop a functional model for the synthesis of nanostructures of the given quality level, which will allow to effectively control the process of nanopatterning on the surface of semiconductors with tunable properties. Design/methodology/approach: The paper uses the IDEF0 methodology, which focuses on the functional design of the system under study and describes all the necessary processes with an accuracy sufficient for an unambiguous modelling of the system's activity. Based on this methodology, we have developed a functional model for the synthesis of nanostructures of the given quality level and tested its effectiveness through practice. Findings: The paper introduces a functional model for the synthesis of nanostructures on the surface of the given quality level semiconductors and identifies the main factors affecting the quality of nanostructures as well as the mechanisms for controlling the formation of porous layers with tunable properties. Using the example of etching single-crystal indium phosphide electrochemically in a hydrochloric acid solution, we demonstrate that the application of the suggested model provides a means of forming nanostructures with tunable properties, assessing the quality level of the nanostructures obtained and bringing the parameters in line with the reference indicators at a qualitatively new level. Research limitations/implications: Functional modelling using the IDEF0 methodology is widely used when process control is required. In this study it has been applied to control the synthesis of nanostructures of the given quality level on the surface of semiconductors. However, these studies require continuation, namely, the establishment of correlations between the technological and resource factors of synthesis and the acquired properties of nanostructures. Practical implications: This study has a significant practical effect. Firstly, it shows that functional modelling can reduce the time required to form large batches of the given quality level nanostructures. This has made it possible to substantiate the choice of the initial semiconductor parameters and nanostructure synthesis modes in industrial production from the theoretical and empirical perspective. Secondly, the presented methodology can be applied to control the synthesis of other nanostructures with desired properties and to reduce the expenses required when resources are depleted and the cost of raw materials is high. Originality/value: This paper is the first to apply the IDEF0 methodology to control the given quality nanostructure synthesis. This paper will be of value to engineers who are engaged in the synthesis of nanostructures, to researchers and scientists as well as to students studying nanotechnology.
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Leach, Gary W., Sasan V. Grayli, Finlay MacNab, Xin Zhang i Saeid Kamal. "Hot Electron Extraction Enabled By Single-Crystal Metal Films and Nanostructures". ECS Meeting Abstracts MA2022-01, nr 13 (7.07.2022): 925. http://dx.doi.org/10.1149/ma2022-0113925mtgabs.
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In contrast to conventional photovoltaic devices which rely on bulk semiconductor material absorption and separation of electron-hole pairs, surface plasmon-based solar energy harvesting employs rectifying metal/dielectric interfaces to capture light and separate charges. Here, we describe the requirements for efficient hot electron extraction in plasmonic photovoltaic devices and demonstrate a new scalable and environmentally friendly electroless deposition method for single-crystal epitaxial noble metals films and nanostructures. The method produces ultra-smooth, low loss, single-crystal noble metal films ideal for subtractive patterning of nanostructures through ion beam milling, and high definition, sub-wavelength single crystal nanostructures through lithographic patterning methods. We describe the nucleation and growth of these metal films and nanostructures in the absence and presence of anionic shape-control agents and examine the role of specific anions in determining the resulting film and nanostructure morphologies via scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). These effects have been exploited to yield large area patterned, and shape-controlled nanoarrays of single crystal metal nanostructures for plasmonic and metamaterial applications. These approaches offer new and cost effective routes to achieve crystalline, shape-controlled surface nanostructure to enable efficient hot electron extraction for energy harvesting and catalysis applications and new noble metal alloys for improved electrocatalysis.
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Yoon, Sang-Hyeok, i Kyo-Seon Kim. "Doping Mo on Tungsten Oxide Thin Film and Photoelectrochemical Measurement". Journal of Nanoscience and Nanotechnology 21, nr 9 (1.09.2021): 4813–17. http://dx.doi.org/10.1166/jnn.2021.19256.
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Tungsten oxide (WO3) is semiconductor material which can be used for various applications. Especially, one-dimensional (1-D) nanostructured WO3 shows the high photoelectrochemical (PEC) performance due to high surface area and short transport route of electron–hole pair. The flame vapor deposition (FVD) process is an efficient and economical method for preparation of the 1-D nanos-tructured WO3 thin film. Molybdenum doping is a well-known method to improve the PEC performance of WO3 by reducing band gap and increasing electrical property. In this study, we prepared the 1-D WO3 nanostructures doped with Mo by FVD single step process. We confirmed that Mo was successfully doped on WO3 without changing significantly the original nanostructure, crystal structure and chemical bonding state of WO3 thin film. As a result of PEC measurement, the pho-tocurrent densities of WO3 thin film with Mo doping were higher by about 1.4 to 2 times (for applied voltage above 0.7 V vs. SCE) than those without Mo doping.
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Gyanwali, Gunanidhi. "Studying the Effect of Seed-layers of Zinc Oxide Nanostructured Thin Film for Liquefied Petroleum Gas Sensor Application". Molung Educational Frontier 10 (31.12.2020): 41–49. http://dx.doi.org/10.3126/mef.v10i0.34056.
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Gas sensors are devices that can convert the concentration of an analyte gas into an electronic signal. Zinc oxide (ZnO) is one of the most important n-type metal oxide semiconductor which has been utilized as gas sensor for many years. In this work, ZnO nanostructured films were synthesized by a hydrothermal growth from ZnO seeds and used as a liquefied petroleum gas (LPG) sensor. At first ZnO seed layers were deposited on glass substrates by using spin coating method, then ZnO nanostructured were grown on these substrates by using hydrothermal growth method. The effect of seed layers of ZnO nanostructured on its structural, optical, and electrical properties was studied. These nanostructures were characterized by scanning electron microscopy, X-ray diffraction, optical spectroscopy, and sheet resistance measurement unit. The sensing performances of the synthetic ZnO nanostructures were investigated for LPG. XRD showed that all the ZnO nanostructures were hexagonal crystal structure. ZnO nanostructured thin film showed high sensitivity towards LPG gas. The sensitivity of the film is observed to increase with increase in number of seed layers. The sensitivity of the film was investigated by measured change in sheet resistance under with LPG gas.
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Galoppini, Elena. "(Invited) Bridge Design for Photoactive Molecules at Interfaces". ECS Meeting Abstracts MA2018-01, nr 31 (13.04.2018): 1849. http://dx.doi.org/10.1149/ma2018-01/31/1849.
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Electron transfer at the interface between a photoactive molecule and large bandgap nanostructured metal oxide semiconductors (ZnO, TiO2 for instance) remains at the center of intense research in numerous areas of solar energy conversion. Such areas encompass photocatalysis and solar fuels, photovoltaics, energy storage, and artificial photosynthesis. An enduring challenge is the ability to achieve control of the chromophore/semiconductor interface at the molecular level. The goal of our collaborative research is to address it by a combination of synthetic design and interfacial charge transfer studies. The presentation will describe the development of “functional” linkers for chromophore-linker model compounds that are able to tune and control the energy level alignment of molecules on nanostructured or single crystal inorganic semiconductors.
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Jagerová, Adéla, Josef Flaks, Zdeněk Sofer, Marek Vronka, Alena Michalcová i Anna Macková. "The synthesis of Au-NPs by ion implantation in the crystalline GaN and characterisation of their optical properties". EPJ Web of Conferences 261 (2022): 01003. http://dx.doi.org/10.1051/epjconf/202226101003.
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Nanostructured surfaces with embedded noble metal nanoparticles is an attractive way for manipulation with the optical properties of wide bandgap semiconductors applied in optoelectronics, photocatalytic processes or for Surface-Enhanced Raman spectroscopy. Ion implantation offers an effective way for nanoparticle preparation without the use of additional chemicals that offers precise control of nanoparticle depth distribution. The aim of this study is a synthesis of the gold nanoparticles in GaN by implantation of 1.85 MeV Au ions with high fluences up to 7×1016 cm-2 and study of optical properties of Au implanted GaN. Implanted crystals were annealed at 800 °C in an ammonia atmosphere for 20 min to support Au nanoparticle creation and GaN recovery. The structure characterisation has been realized by Rutherford backscattering spectroscopy in channelling mode and it showed the formation of two separated disordered regions – the surface region and buried layer. The lower implantation fluences induce damage mainly in a buried layer; however, the increase of the Au-ion fluence leads to the increase of surface disorder as well. Further, the increase of the Au-ion fluence induces the Au dopant shift to the surface and multimodal Audepth profiles. TEM analyses confirmed the formation of Au nanoparticles in the implanted samples after annealing with sizes up to 14 nm. The increase of light absorption and modification of GaN bandgap of the Au modified GaN was deduced from the change in optical transmission spectra between 370 – 1400 nm.
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Coridan, Robert H., Mya A. Norman i Hamed Mehrabi. "Enhanced light absorption in simulations of ultra-thin ZnO layers structured by a SiO2 photonic glass". Canadian Journal of Chemistry 96, nr 11 (listopad 2018): 969–73. http://dx.doi.org/10.1139/cjc-2018-0218.
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Hierarchically organized nanostructures are often employed to improve the energy conversion efficiency of photovoltaic and photoelectrochemical cells. Ultra-thin semiconductors can improve the internal carrier collection yield in materials with poor carrier lifetimes by reducing the characteristic length scales of collection. However, reducing the dimension of the light absorber requires strategies to increase absorption and the overall photogeneration when the material is to be used in broadband solar energy conversion applications. Here, we explore a strategy for improving light absorption in nanometer-scale, ultra-thin film ZnO layers by integrating them into a SiO2 colloidal crystal-based photonic glass. We use three-dimensional finite-difference electromagnetic simulations to study the local and total absorption improvements on composite films of close-packed, randomized colloidal structures coated with a thin layer of ZnO. These simulations show that the near band-gap absorption in the ZnO coating is dependent on the degree of vacancies in the colloidal crystal that templates the photonic glass. With these results, we show that disordered, defective colloidal composites can potentially be used to fabricate nanostructured photoelectrodes based on ultra-thin semiconductor layers with improved light absorption characteristics.
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Srivani, Dr Alla, Gurram Vasanth, Dr GVS Subbaroy Sharma, M. Srinivasa Rao i Dr P. Ramesh. "Advanced Semiconductor Alloy Alxin1-Xp for Engineering and Medicine". Journal of Community Pharmacy Practice, nr 25 (14.09.2022): 1–5. http://dx.doi.org/10.55529/jcpp.25.1.5.
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Doped Advanced semiconductor materials with different properties are useful for early diagnosis and improved treatment in medical research. This is essential for advanced medical technology and lower mortality rates. New research on impurity-doped nano crystals is important. These dopants can directly affect electron transport in semiconductors, tune the optical properties of nano materials in desirable ways, and impart specific properties to the host. In this research report, we first discuss the factors that need to be considered to systematically control the production of these doped semiconductor materials, then describe various doped materials and typical synthetic approaches and techniques. Innovations in nanotechnology and materials design and their application in early diagnosis and treatment are believed to minimize the number of new cases of related diseases and reduce mortality.1,2,3 From natural to man-made materials, Doped semiconductor nanostructures, including inorganic and organic semiconductors, are increasingly attracting the attention of researchers and scientists worldwide
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Slamet, Domo, Didik Krisdiyanto i Khamidinal Khamidinal. "Synthesis of ZnO Nanoparticles Doped Zirconium Oxychloride by PSTA BATAN Yogyakarta Production as Photoanode Semiconduktors for Dye Sensitized Solar Cell". Proceeding International Conference on Science and Engineering 1 (31.10.2017): 91–97. http://dx.doi.org/10.14421/icse.v1.276.
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Dye Sensitized Solar Cell (DSSC) is a device for light conversion to be electrical energy based on the concept of semiconducting sensitivity of the wide gap. This study aims to synthesis nanoparticles of ZnO: Zr semiconductors and tested the performance of ZnO: Zr nanoparticles on the DSSC system. ZnO Doped Zr Nanoparticles from precursor by Science and Technology Acceleration Center of National Nuclear Energy Agency (PSTA BATAN) Yogyakarta production was synthesized by gel-combustion method, and tested its performance on DSSC system. Effect of doping concentration variation Zr (0, 1, 3 and 5%) on the structure crystals and optical properties of ZnO studied by X-ray diffraction, infra-red spectra, and UV-Visible absorbance spectra. In this study also studied about the effect of Zr doping on changes in the parameters of crystal structures such as distances between fields of crystals , crystals lattice (a and c), unit cell volume, crystallite size, microstrain (ε), dislocation density (δ), and the textural coefficient . The synthesized nanoparticles meet the criteria 3-dimensional nanostructure of hexagonal wurtzite crystals. Uptake ZnO infrared radiation shows an increase in intensity as well shift in wave number 610 - 400 due to doping Zr. Doping Zr also influences the electronic structure of semiconductors characterized by the change of bandgap energy from 3,10-3,05 eV. Semiconductor performance test nanoparticles on the DSSC system showed a 1% Zr doping concentration increasing the voltage by 174 mV and the stability of the solar cell than the cell ZnO solar without doping that produces a voltage of 128 mV.
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FAN, Z., i J. G. LU. "Nanostructured ZnO: Building Blocks for Nanoscale Devices". International Journal of High Speed Electronics and Systems 16, nr 04 (grudzień 2006): 883–96. http://dx.doi.org/10.1142/s0129156406004065.
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ZnO is attracting intensive attention for its versatile applications in transparent electronics, UV emitter, piezoelectric devices, chemical sensor and spin electronics. As one of the direct wide band gap semiconductors, it has advantages over GaN due to its larger exciton binding energy, better lattice match on heteroepitaxial growth and availability of single crystal substrate. Large effort has been invested in the growth of nanostructured ZnO to explore its potentials for nanoscale device applications. ZnO nanobelts, nanowires, nanorings, and nanohelixes demonstrate the diversity of ZnO nanostructures family. This review presents recent research on ZnO nanostructures. Issues of synthesis methods, optical, electrical, gas sensing and magnetic properties are summarized. These progresses constitute the basis for developing future applications in nanoscale electronics, optoelectronics, chemical sensor and spintronics.
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Zheng, Yiran, Min Li, Xiaoyan Wen, Ho-Pui Ho i Haifei Lu. "Nanostructured ZnO/Ag Film Prepared by Magnetron Sputtering Method for Fast Response of Ammonia Gas Detection". Molecules 25, nr 8 (20.04.2020): 1899. http://dx.doi.org/10.3390/molecules25081899.
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Possessing a large surface-to-volume ratio is significant to the sensitive gas detection of semiconductor nanostructures. Here, we propose a fast-response ammonia gas sensor based on porous nanostructured zinc oxide (ZnO) film, which is fabricated through physical vapor deposition and subsequent thermal annealing. In general, an extremely thin silver (Ag) layer (1, 3, 5 nm) and a 100 nm ZnO film are sequentially deposited on the SiO2/Si substrate by a magnetron sputtering method. The porous nanostructure of ZnO film is formed after thermal annealing contributed by the diffusion of Ag among ZnO crystal grains and the expansion of the ZnO film. Different thicknesses of the Ag layer help the formation of different sizes and quantities of hollows uniformly distributed in the ZnO film, which is demonstrated to hold superior gas sensing abilities than the compact ZnO film. The responses of the different porous ZnO films were also investigated in the ammonia concentration range of 10 to 300 ppm. Experimental results demonstrate that the ZnO/Ag(3 nm) sensor possesses a good electrical resistance variation of 85.74% after exposing the sample to 300 ppm ammonia gas for 310 s. Interestingly, a fast response of 61.18% in 60 s for 300 ppm ammonia gas has been achieved from the ZnO/Ag(5 nm) sensor, which costs only 6 s for the response increase to 10%. Therefore, this controllable, porous, nanostructured ZnO film maintaining a sensitive gas response, fabricated by the physical deposition approach, will be of great interest to the gas-sensing community.
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Savchuk, Andriy I., Volodymyr I. Fediv, Tetyana A. Savchuk, Ihor D. Stolyarchuk, Yevheniy O. Kandyba, Dmytro I. Ostafiychuk, Svitlana A. Ivanchak i Vitaliy V. Makoviy. "Optical and Magneto-Optical Studies of Composite Materials Containing Semimagnetic Semiconductor Nanoparticles". Solid State Phenomena 151 (kwiecień 2009): 259–63. http://dx.doi.org/10.4028/www.scientific.net/ssp.151.259.
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Сomposite films containing II-VI based semiconductor nanoparticles have been prepared by different physical and chemical techniques. Non-magnetic CdS1-xSex nanoparticles were grown by melting of the semiconductor doped fine powder borosilicate glass. The composite semimagnetic semiconductor Cd1-xMnxTe based films were fabricated by embedding in SiO2 matrix with using of pulsed laser deposition technique. New chemical approach to synthesis of Cd1-xMnxS nanoparticles in polymer matrix has been proposed. The optical absorption edge for CdS1-xSex , Cd1-xMnxTe nanoparticles and exciton structure in the spectrum of Cd1-xMnxS nanoparticles shifted to the higher-energy side compared to those for bulk crystals due to the quantum confinement effect. Magneto-optical Faraday effect for non-magnetic semiconductor nanoparticles in glass demonstrates only small changes as compared with that of bulk semiconductors. The revealed peculiarities in spectral and magnetic field dependences of the Faraday rotation for the studied semimagnetic semiconductor composite films can be attributed to the influence of dimensionality on spin exchange parameters for such kind of nanostructures.
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Al-Salman, Rihab, Xiangdong Meng, Jiupeng Zhao, Yao Li, Ulrich Kynast, Marina M. Lezhnina i Frank Endres. "Semiconductor nanostructures via electrodeposition from ionic liquids". Pure and Applied Chemistry 82, nr 8 (14.05.2010): 1673–89. http://dx.doi.org/10.1351/pac-con-09-09-25.
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The fascinating properties of ionic liquids make it possible to synthesize semiconductor nanostructures via a simple and low-cost electrochemical pathway. The present paper summarizes our recent work on the synthesis of Si, Ge, and SixGe1–x nanostructures from ionic liquids: thin films, nanowires and photonic crystals. We also introduce our first results on the template-assisted electrodeposition of SixGe1–x photonic crystals from 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([EMIm]Tf2N) ionic liquid, and some optical measurements on the previously prepared Ge photonic crystals. Our results confirm that electrochemistry in ionic liquids is excellently suited to the synthesis of high-quality semiconductor nanostructures.
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Kamanina, Natalia. "Carbon Nanotube Coatings’ Role in Transparency, Mechanical Hardness, and Wetting Angle Increase". Coatings 12, nr 9 (1.09.2022): 1279. http://dx.doi.org/10.3390/coatings12091279.
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Among the different nanostructures involved in the improvement of material properties, carbon nanotubes occupy a specific place because of their small refractive index, extended surface, and large Young’s module, which can all provoke dramatic change in basic matrix material characteristics. Inorganic crystals, semiconductors, metals, conductive compounds, and some polymer structures whose surfaces are treated with carbon nanotubes demonstrate better features than the ones obtained before carbon nanotubes deposition. Thus, the areas of application for these unique nanostructure materials can be effectively extended, e.g., for optoelectronic use, in biomedicine, and display applications. In the current paper, the advantages of the laser-oriented deposition technique are shown in order to demonstrate how the main material parameters change drastically through the incorporation of carbon nanotubes.
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Wen, Zhuoqun, Yiping Wang, Zhizhong Chen i Jian Shi. "Chemical Vapor Growth of Silicon Phosphide Nanostructures". MRS Advances 5, nr 31-32 (25.11.2019): 1653–60. http://dx.doi.org/10.1557/adv.2019.437.
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ABSTRACTIn the search for chemically stable two-dimensional (2D) materials with high in-plane mobility, proper bandgap, and compatibility with vapor-based fabrication, van der Waals semiconductor SiP has become a potential candidate as a robust variation of black phosphorous. While bulk SiP crystals were synthesized in the 1970s, the vapor-based synthesis of SiP nanostructures or thin films is still absent. We here report the first chemical vapor growth of SiP nanostructures on SiO2/Si substrate. SiP islands with lateral size up to 20 μm and showing well-defined Raman signals were grown on SiO2/Si substrate or on SiP-containing concentric rings. The presence of SiP phase is confirmed by XRD. The formation of rings and islands is explained by a multiple coffee ring growth model where a dynamic fluctuation of droplet growth front induces the topography of concentric ring surfaces. This new growth method might shed light on the controlled growth of group IV-III high-mobility 2D semiconductors.
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Prabhakar Vattikuti, Surya V., Jie Zeng, Rajavaram Ramaraghavulu, Jaesool Shim, Alain Mauger i Christian M. Julien. "High-Throughput Strategies for the Design, Discovery, and Analysis of Bismuth-Based Photocatalysts". International Journal of Molecular Sciences 24, nr 1 (30.12.2022): 663. http://dx.doi.org/10.3390/ijms24010663.
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Bismuth-based nanostructures (BBNs) have attracted extensive research attention due to their tremendous development in the fields of photocatalysis and electro-catalysis. BBNs are considered potential photocatalysts because of their easily tuned electronic properties by changing their chemical composition, surface morphology, crystal structure, and band energies. However, their photocatalytic performance is not satisfactory yet, which limits their use in practical applications. To date, the charge carrier behavior of surface-engineered bismuth-based nanostructured photocatalysts has been under study to harness abundant solar energy for pollutant degradation and water splitting. Therefore, in this review, photocatalytic concepts and surface engineering for improving charge transport and the separation of available photocatalysts are first introduced. Afterward, the different strategies mainly implemented for the improvement of the photocatalytic activity are considered, including different synthetic approaches, the engineering of nanostructures, the influence of phase structure, and the active species produced from heterojunctions. Photocatalytic enhancement via the surface plasmon resonance effect is also examined and the photocatalytic performance of the bismuth-based photocatalytic mechanism is elucidated and discussed in detail, considering the different semiconductor junctions. Based on recent reports, current challenges and future directions for designing and developing bismuth-based nanostructured photocatalysts for enhanced photoactivity and stability are summarized.
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WABNITZ, S. "SIGNAL PROCESSING IN PHOTONIC CRYSTALS AND NANOSTRUCTURES". Journal of Nonlinear Optical Physics & Materials 15, nr 01 (marzec 2006): 55–76. http://dx.doi.org/10.1142/s0218863506003165.
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Optical devices employing photonic crystals and novel nanostructure materials may exhibit useful properties for applications to all-optical signal processing. In this work we analyze as a first example four-wave mixing of polarized beams in photonic crystal fibers. We show that by properly tuning the pump wavelength and the linear dispersion properties of the fiber one may obtain broadband parametric amplification and frequency conversion. Next we consider the in-line periodic amplification of short optical pulses by means of quantum-dot semiconductor optical amplifiers. We show by numerical simulations that pattern-free amplification of a 40 Gbit/s soliton signal at 1300 nm is possible without any inter-symbol interference or nonlinear pulse distortion caused by the fast gain dynamics.
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Dahal, Pabitra, Jeffrey Chou, Yu Wang, Sang Gook Kim i Jaime Viegas. "Comparative study of multilayered nanostructures for enhanced solar optical absorption". MRS Advances 1, nr 13 (2016): 839–45. http://dx.doi.org/10.1557/adv.2016.7.
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ABSTRACTImproved solar spectrum optical absorption in multilayered nanostructures consisting of metal, semiconductor and dielectric layers increase their potential for efficient photon to electron conversion. In this work, we analyze the influence of different nanostructure shapes and dimensions on the optical absorption in the vacuum wavelength range of 400 nm to 1500 nm based on Finite Domain Time Difference (FDTD) method. A periodic metallic photonic crystal composed of nanorods of gold, titanium oxide, and alumina is proposed by optimizing thickness of Au and TiO2, aspect ratio, sidewall angle, and geometry of the elemental shape. A high aspect ratio structure consisting of elliptical nose cone elements with optimized dimensions is seen to absorb more than 90% of the solar spectrum in the range considered.
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Maitra, Soumyajit, Arundhati Sarkar, Toulik Maitra, Somoprova Halder, Subhasis Roy i Kajari Kargupta. "Cadmium Sulphide Sensitized Crystal Facet Tailored Nanostructured Nickel Ferrite @ Hematite Core-Shell Ternary Heterojunction Photoanode for Photoelectrochemical Water Splitting". MRS Advances 5, nr 50 (2020): 2585–93. http://dx.doi.org/10.1557/adv.2020.316.
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AbstractDesign of composite semiconductor nanostructures with proper band alignment for efficient charge separation and carrier transport has been at the center of research for photoelectrochemical water splitting. This work demonstrates the deposition of a NiFe2O4 @Fe2O3 core-shell nanostructured film sensitized with CdS to form a ternary heterojunction for cascade type electron transfer. The hematite nanostructures were grown by hydrothermal approach through dipping into a solution of Nickel Nitrate yielded anchoring of Ni2+ ions on the outer surface. The films were then annealed at 650 0C for the diffusion of Ni2+ ions into the hematite lattice which forms core-shell NiFe2O4 @Fe2O3 heterojunction. The films were further sensitized with CdS nanoparticles deposited by a hydrothermal approach to form the final ternary heterojunction photoanode. Several different nanostructures were grown and the effect of crystal facet tailoring was observed on Ni loading and photoelectrochemical performance. The photoelectrochemical measurements were carried out using a potentiostat under 100 mW/cm2 light source (150W Xenon Lamp) with Pt counter electrode and 0.5 M Na2S and 0.5 M Na2SO3 electrolyte. A current density of 3.47 mA/cm2 was observed at 1.23 V (vs Ag/AgCl). An Applied Bias to Photocurrent Efficiency (ABPE) of 1.8 % photoconversion efficiency was observed using the fabricated electrodes at 0.288V (vs Ag/AgCl).
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Wang, Hsin-Yi, Jiazang Chen, Fang-Xing Xiao, Jianwei Zheng i Bin Liu. "Doping-induced structural evolution from rutile to anatase: formation of Nb-doped anatase TiO2nanosheets with high photocatalytic activity". Journal of Materials Chemistry A 4, nr 18 (2016): 6926–32. http://dx.doi.org/10.1039/c5ta08202a.
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Volokh, Michael, i Taleb Mokari. "Metal/semiconductor interfaces in nanoscale objects: synthesis, emerging properties and applications of hybrid nanostructures". Nanoscale Advances 2, nr 3 (2020): 930–61. http://dx.doi.org/10.1039/c9na00729f.
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Multi-component crystals of various shapes, sizes and compositions (hybrid nanostructures) are much sought-after functional materials. Herein, the synthesis and emerging properties of nanomaterials with metal/semiconductor interface(s) are reviewed.
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Kim, M. J., L. C. Liu, S. H. Risbud i R. W. Carpenter. "Nanostructure of semiconductor quantum dots in a borosilicate glass matrix by complementary use of HREM and AEM". Proceedings, annual meeting, Electron Microscopy Society of America 48, nr 4 (sierpień 1990): 728–29. http://dx.doi.org/10.1017/s0424820100176770.
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When the size of a semiconductor is reduced by an appropriate materials processing technique to a dimension less than about twice the radius of an exciton in the bulk crystal, the band like structure of the semiconductor gives way to discrete molecular orbital electronic states. Clusters of semiconductors in a size regime lower than 2R {where R is the exciton Bohr radius; e.g. 3 nm for CdS and 7.3 nm for CdTe) are called Quantum Dots (QD) because they confine optically excited electron- hole pairs (excitons) in all three spatial dimensions. Structures based on QD are of great interest because of fast response times and non-linearity in optical switching applications.In this paper we report the first HREM analysis of the size and structure of CdTe and CdS QD formed by precipitation from a modified borosilicate glass matrix. The glass melts were quenched by pouring on brass plates, and then annealed to relieve internal stresses. QD precipitate particles were formed during subsequent "striking" heat treatments above the glass crystallization temperature, which was determined by differential thermal analysis.
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Lee, Jae-Ho, Kwonwoo Oh, Kyungeun Jung, K. C. Wilson i Man-Jong Lee. "Tuning the Morphology and Properties of Nanostructured Cu-ZnO Thin Films Using a Two-Step Sputtering Technique". Metals 10, nr 4 (27.03.2020): 437. http://dx.doi.org/10.3390/met10040437.
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Zinc oxide (ZnO) is a wide-band-gap semiconductor that is promising for use as a transparent conductive oxide film. To date, to improve their optoelectrical properties, pristine ZnO films have been doped with metals using various techniques. In this study, nanostructured Cu-ZnO thin films were synthesized using a modified two-step radio frequency magnetron sputtering technique with separate ZnO and metallic Cu targets. Controlling the timing of the Cu/ZnO co-sputtering and ZnO-only sputtering steps afforded a significant change in the resulting nanostructures, such as uniform Cu-ZnO and broccoli-structured Cu-ZnO thin films. Using various measurement techniques, the influence of Cu doping was analyzed in detail. Furthermore, a crystal growth model for the formation of the broccoli-like clusters was suggested. The Cu-ZnO thin films synthesized using this technique demonstrate a highly improved conductivity with some loss in optical transmittance.
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Guo, Liejin, Dengwei Jing, Maochang Liu, Yubin Chen, Shaohua Shen, Jinwen Shi i Kai Zhang. "Functionalized nanostructures for enhanced photocatalytic performance under solar light". Beilstein Journal of Nanotechnology 5 (9.07.2014): 994–1004. http://dx.doi.org/10.3762/bjnano.5.113.
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Photocatalytic hydrogen production from water has been considered to be one of the most promising solar-to-hydrogen conversion technologies. In the last decade, various functionalized nanostructures were designed to address the primary requirements for an efficient photocatalytic generation of hydrogen by using solar energy: visible-light activity, chemical stability, appropriate band-edge characteristics, and potential for low-cost fabrication. Our aim is to present a short review of our recent attempts that center on the above requirements. We begin with a brief introduction of photocatalysts coupling two or more semiconductors, followed by a further discussion of the heterostructures with improved matching of both band structures and crystal lattices. We then elaborate on the heterostructure design of the targeted materials from macroscopic regulation of compositions and phases, to the more precise control at the nanoscale, i.e., materials with the same compositions but different phases with certain band alignment. We conclude this review with perspectives on nanostructure design that might direct future research of this technology.
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López-López, Máximo, Esteban Cruz-Hernández, Isaac Martínez-Velis, Juan Salvador Rojas-Ramírez, Manolo Ramirez-Lopez i Álvaro Orlando Pulzara-Mora. "Self Assembly of semiconductor nanostructures". Respuestas 12, nr 2 (16.05.2016): 47–51. http://dx.doi.org/10.22463/0122820x.570.
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Abstract In this work we present the growth and characterization of GaAs self-assembled quantum wires (SAQWRs), and InAs self-assembled quantum dots (SAQDs) by molecular beam epitaxy on (631)-oriented GaAs substrates. Adatoms on the (631) crystal plane present a strong surface diffusion anisotropy which we use to induce preferential growth along one direction to produce SAQWRs. On the other hand, InAs SAQDs were obtained on GaAs(631) with SAQWRs by the Stransky–Krastanov (S-K) growth method. SAQDs grown directly on (631) substrates presented considerable fluctuations in size. We study the effects of growing a stressor layer before the SAQDs formation to reduce these fluctuations.Keywords : Quantum wires, quantum dots; selfassembly; molecular beam epitaxy.
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Yang, C. C., i S. Li. "Size Dependence of Optical Properties in Semiconductor Nanocrystals". Key Engineering Materials 444 (lipiec 2010): 133–62. http://dx.doi.org/10.4028/www.scientific.net/kem.444.133.
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An extension of the classic thermodynamic theory to nanometer scale has generated a new interdisciplinary theory - nanothermodynamics. It is the critical tool for the investigation of the size-dependent physicochemical properties in nanocrystals. A simple and unified nanothermodynamic model for the melting temperature of nanocrystals has been established based on Lindemann’s criterion for the melting, Mott’s expression for the vibrational melting entropy, and Shi’s model for the size dependence of the melting point. The developed model has been extensively verified in calculating a variety of size- and dimensionality-dependent phase transition functions of nanocrystals. In this work, such a model was extended to explain the underlying mechanism behind the bandgap energy enhancement and Raman red shifts in semiconductor nanocrystals by (1) investigating the crystal size r, dimensionality d, and constituent stoichiometry x dependences of bandgap energies Eg in semiconductor quantum dots (QDs) and quantum wires (QWs); and (2) revealing the origin of size effect on the Raman red shifts in low dimensional semiconductors by considering the thermal vibration of atoms. For Eg, it is found that: (1) Eg increases with a decreasing r for groups IV, III-V and II-VI semiconductors and the quantum confinement effect is pronounced when r becomes comparable to the exciton radius; (2) the ratio of Eg(r, d)QWs/Eg(r, d)QDs is size-dependent, where Eg(r, d) denotes the change in bandgap energy; (3) the crystallographic structure (i.e. zinc-blende and wurtzite) effect on Eg of III-V and II-VI semiconductor nanocrystals is limited; and (4) for both bulk and nanosized III-V and II-VI semiconductor alloys, the composition effects on Eg are substantial, having a common nonlinear (bowing) relationship. For the Raman red shifts, the lower limit of vibrational frequency was obtained by matching the calculation results of the shifts with the experimental data of Si, InP, CdSe, CdS0.65Se0.35, ZnO, CeO2, as well as SnO2 nanocrystals. It shows that: (1) the Raman frequency (r) decreases as r decreases in both narrow and wide bandgap semiconductors; (2) with the same r, the sequence of size effects on (r) from strong to weak is nanoparticles, nanowires, and thin films; and (3) the Raman red shift is caused by the size-induced phonon confinement effect and surface relaxation. These results are consistent with experimental findings and may provide new insights into the size, dimensionality, and composition effects on the optical properties of semiconductors as well as fundamental understanding of high-performance nanostructural semiconductors towards their applications in optoelectronic devices.
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Anufriev, Roman, i Masahiro Nomura. "Coherent Thermal Conduction in Silicon Nanowires with Periodic Wings". Nanomaterials 9, nr 2 (22.01.2019): 142. http://dx.doi.org/10.3390/nano9020142.
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Artificial periodic nanostructures, known as phononic crystals, promise to control the thermal properties of nanostructures in the coherent regime, which can be achieved in semiconductors at low temperatures. Here, we study coherent thermal conduction in silicon nanowires with added periodic wings at sub-Kelvin temperature. Our simulations show that the added periodic wings flatten the phonon dispersion and thus reduce the thermal conductance. We investigate the dependence of this reduction on the size of the wings and conclude that the reduction is mainly caused by the periodicity of the wings, rather than by local resonances in them. These findings help to better understand the mechanisms controlling coherent heat conduction in periodic resonant nanostructures.
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Magnussen, Olaf M. "(Invited) Atomic-Scale Aspects of Nucleation and Growth at Liquid-Liquid Interfaces". ECS Meeting Abstracts MA2022-01, nr 23 (7.07.2022): 1152. http://dx.doi.org/10.1149/ma2022-01231152mtgabs.
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Interfaces between liquid metals and liquid electrolytes, in particular the liquid Hg - electrolyte interface, have played a key role in the development of the theory of the electrical double layer and electrochemical adsorption. More recently, liquid-liquid interfaces have regained interest in the field of material synthesis. Unlike solid interfaces, where strain and stress, heterogeneities, and defects strongly influence growth processes, fluid systems provide soft, defect- and stress-free interfaces. In addition, the growth process profits from the high mobility of atoms, molecules, and particles in both liquids, which allows growth from both sides of the phase boundary. A large variety of metallic and non-metallic nanomaterials has been prepared via electrochemical and electroless deposition at such liquid-liquid interfaces. As demonstrated by Maldonado and coworkers, electrodeposition at liquid metal electrodes even allows the growth of nanostructured crystalline semiconductors via a simple one-step, room-temperature electrochemical process [1]. Understanding of the fundamental processes in nucleation and growth at liquid-liquid interfaces is hampered by difficulties in studying these interfaces experimentally on the atomic scale. Most surface-sensitive techniques, especially also scanning probe microscopy methods, cannot access these fluidic phase boundaries. For this reason, the majority of studies relies on electrochemical measurements, optical microscopy, and ex situ investigation of the deposit and thus provide little insight on the initial steps of the growth process. We have shown in the past that hard X-ray scattering methods, such as X-ray reflectivity (XRR) and grazing incidence X-ray scattering (GIXS), are unique tools for determining the atomic liquid-liquid interface structure. In this talk, we present case studies of electrochemically induced growth at liquid interfaces from the first monolayer up to several ten nanometer thick films. The first part discusses the growth of ionic compounds, using lead halides on Hg electrodes as an example. In PbBr2 containing NaF we observed previously growth of a PbBrF layer by operando X-ray scattering. This growth exhibited a complex nucleation and growth behavior, involving a crystalline precursor layer prior to 3D crystal growth [2]. The well-defined subnanometer thick precursor layer provided a template for the subsequent quasi-epitaxial growth of oriented 3D crystallites. Detailed studies on the potential-dependent nucleation and growth kinetics revealed with increasing overpotential a crossover from a low surface density film of large crystals to a compact PbBrF deposit with a saturation thickness of 25 nm [3,4]. In addition, growth on the liquid substrate was found to involve micromechanical effects, such as crystal reorientation and film breakup during dissolution. More recently, we extended these studies to growth in solutions containing only one type of halide anion (Br, Cl, or F). Also here, the formation of precursor layers was observed, indicating that this growth behavior is a general phenomenon. In the second part, joint X-ray scattering studies with Maldonado and coworkers on the electrochemical liquid-liquid-solid deposition of semiconductors from aqueous electrolyte are presented, focusing on Ge electrodeposition on Hg and HgxIn1-x alloy electrodes [5]. We provide evidence for the adsorption of GeO3 - anions on the liquid metal surface and the formation of a crystalline GeO2 adlayer at the positive end of the double layer region. Ge electrodeposition results in nanocrystals, which are separated from the Hg electrode by a water cushion. Furthermore, pronounced Hg surface segregation is found in HgxIn1-x, which protects the electrode surface from oxidation in the potential regime of Ge deposition. [1] Carim, A. I., Collins, S. M., Foley, J. M. & Maldonado, J. Am. Chem. Soc. 133, 13292 (2011) [2] A. Elsen, S. Festersen, B. Runge, C.T. Koops, B. M. Ocko, M. Deutsch, O. Seeck, B. M. Murphy, O. M. Magnussen, Proc. Nat. Acad. Sci., 110, 6663 (2013) [3] B.M. Murphy, S. Festersen, O.M. Magnussen, Nanoscale, 8, 13859 (2016) [4] S. Festersen, B. Runge, C. Koops, F. Bertram, B.M. Ocko, M. Deutsch, B.M. Murphy, O.M. Magnussen, Langmuir, 36, 10905 (2020) [5] D. Pattadar, Q. Cheek, A. Satori, Y. Zhao, P.R. Giri, B. Murphy, O.M. Magnussen, S. Maldonado, Cryst. Growth Des., 21, 1645 (2021)
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Румянцев, В. В., К. В. Маремьянин, А. П. Фокин, А. А. Дубинов, А. А. Разова, Н. Н. Михайлов, С. А. Дворецкий, М. Ю. Глявин, В. И. Гавриленко i С. В. Морозов. "Получение терагерцового излучения в кристаллах InP : Fe за счет решеточной нелинейности второго порядка". Физика и техника полупроводников 55, nr 9 (2021): 813. http://dx.doi.org/10.21883/ftp.2021.09.51299.32.
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In this paper, we experimentally demonstrate the generation of the second harmonic radiation of the gyrotron with an operating frequency of 263 GHz due to the second order lattice nonlinearity in indium phosphide crystals doped with ferrum. It is shown that the second harmonic radiation can be used for magnetospectroscopy of semiconductor nanostructures. We discuss the possibility of generating a difference frequency in these crystals when excited by two sources of the mid-IR range with a close wavelength.
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Gusakov, Vasilii E. "A New Approach for Calculating the Band Gap of Semiconductors within the Density Functional Method". Solid State Phenomena 242 (październik 2015): 434–39. http://dx.doi.org/10.4028/www.scientific.net/ssp.242.434.
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Within the framework of the density functional theory, the method was developed to calculate the band gap of semiconductors. We have evaluated the band gap for a number of monoatomic and diatomic semiconductors (Sn, Ge, Si, SiC, GaN, C, BN, AlN). The method gives the band gap of almost experimental accuracy. An important point is the fact that the developed method can be used to calculate both localized states (energy deep levels of defects in crystal), and electronic properties of nanostructures.
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Ahamed, M. I., M. Ahamed, A. Sivaranjani i S. Chockalingam. "Energy bandgap studies on copper chalcogenide semiconductor nanostructures using cohesive energy". Chalcogenide Letters 18, nr 5 (maj 2021): 245–53. http://dx.doi.org/10.15251/cl.2021.185.245.
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Investigating the properties of semiconductor nanomaterials to understand the specific behavior of nano-scale materials and predicts novel advancement of functionalized semiconductor materials that are influenced by cohesive energy. Cohesive energy is strongly associated with semiconductor nanomaterials as the energy increment by the arrangement of atoms in a crystal which is one of the most fundamental properties. In this communication, the shape and size dependence over the energy bandgap of copper chalcogenide semiconductor nanomaterials is investigated. The theoretical model is derived on cohesive energy of semiconductor nanomaterials was equated with the bulk materials. For this research, we considered Cu2SnS3, Cu2SnSe3, Cu2SnTe3, Cu3SbSe4, and CuSbS2 chalcogenide matters to the study of shape and size dependent-energy bandgap. The model forecasts that the energy bandgap is inversely proportional to the size of the semiconductor. The present modeling results are correlated with established experimental data and underpin the model reported.
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Ceja, Israel, Karla Josefina González-Íñiguez, Alejandra Carreón-Álvarez, Gabriel Landazuri, Arturo Barrera, José Eduardo Casillas, Víctor Vladimir A. Fernández-Escamilla i Jacobo Aguilar. "Characterization and Electrical Properties of PVA Films with Self-Assembled Chitosan-AuNPs/SWCNT-COOH Nanostructures". Materials 13, nr 18 (17.09.2020): 4138. http://dx.doi.org/10.3390/ma13184138.
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Nanostructured films with electrical conductivity in the semiconductor region were prepared in a polymeric matrix of poly(vinyl alcohol) (PVA) with nanostructures of chitosan-gold nanoparticles (AuNPs)/single-wall carbon nanotubes carboxylic acid functionalized (SWCNT-COOH) (chitosan-AuNPs/SWCNT-COOH) self-assembled. Dispersion light scattering (DLS) was used to determine the average particle sizes of chitosan-AuNPs, z-average particle size (Dz) and number average particle size (Dn), and the formation of crystalline domains of AuNPs was demonstrated by X-ray diffraction (XRD) patterns and observed by means of transmission electron microscopy (TEM). The electrostatic interaction was verified by Fourier transform infrared spectroscopy (FTIR). The electrical conductivity of PVA/chitosan-AuNPs/SWCNT-COOH was determined by the four-point technique and photocurrent. The calculated Dn values of the chitosan-AuNPs decreased as the concentration of gold (III) chloride trihydrate (HAuCl4·3H2O) increased: the concentrations of 0.4 and 1.3 mM were 209 and 90 nm, respectively. Average crystal size (L) and number average size (D) of the AuNPs were calculated in the range of 13 to 24 nm. Electrical conductivity of PVA/chitosan-AuNPs/SWCNT-COOH films was 3.7 × 10−5 σ/cm determined by the four-point technique and 6.5 × 10−4 σ/cm by photocurrent for the SWCNT-COOH concentration of 0.5 wt.% and HAuCl4·3H2O concentration of 0.4 mM. In this investigation, the protonation of the amine group of chitosan is fundamental to prepare PVA films with nanostructures of self-assembled chitosan-AuNPs/SWCNT-COOH.
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Suchikova, Y., A. Lazarenko, S. Kovachov i I. Bohdanov. "Nanostructures on the ZnSe Surface: Synthesis, Morphological and Photoluminescent Properties". Physics and Chemistry of Solid State 22, nr 4 (10.11.2021): 614–20. http://dx.doi.org/10.15330/pcss.22.4.614-620.
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Nanostructured zinc selenide has been obtained by electrochemical etching with an H2SO4:H2O:H2O5OH=4:1:1 solution used as the electrolyte. The experiment has indicated that the surface consists of two phases, namely the upper layer made up of a dense oxide film and a low-sized porous layer underneath, with a pore diameter of (30-80) nm and a thickness of interporous walls of (15-50) nm. The investigated dependence of surface porosity on the etching time allows us to explain the main stages of the crystal’s electrochemical dissolution during anodizing. The experiment has indicated the presence of three main stages, such as the formation of the Gouy and Helmholtz layers at the semiconductor/electrolyte segregation; pore formation at defect and oxide crystallite locations; spontaneous pore formation. The PL spectra of the samples under study have demonstrated three maxima. The emission band at 2.45 eV is attributable to the presence of oxides, the band at 2.78 EV can be accounted for the corresponding excitons while the band at 2.82 eV stems from quantum-dimensional effects. Chemical analysis of the samples has also indicated the presence of oxides on the surface of the nanostructure.
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Ahmed, Sabah M. "Characterization of Al-doped ZnO nanorods grown by chemical bath deposition method". Innovaciencia Facultad de Ciencias Exactas, Físicas y Naturales 6, nr 1 (28.12.2018): 1–9. http://dx.doi.org/10.15649/2346075x.463.
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Introduction: In recent years a metal oxide semiconductors have been paid attention due to their excellent chemical and physical properties. ZnO (Zinc oxide) is considered as one of the most attractive semiconductor materials for implementation in photo-detectors, gas sensors, photonic crystals, light emitting diodes, photodiodes, and solar cells, due to its novel electrical and optoelectronic properties. There are different uses of metal oxide semiconductors such us, UV photodetectors which are useful in space research’s, missile warning systems, high flame detectors, air quality spotting, gas sensors, and precisely calculated radiation for the treatment of UV-irradiated skin. ZnO is a metal oxide semiconductors and it is used as a transparent conducting oxide thin film because it has the best higher thermal stability, best resistance against the damage of hydrogen plasma processing and relatively cheaper if one compares it with ITO. Materials and Methods: On glass substrates, Al-doped ZnO (AZO) nanorods have been grown by a low -cost chemical bath deposition (CBD) method at low temperature. The seed layer of ZnO was coated on glass substrates. The effect of the Al-doping on the aligned, surface morphology, density, distribution, orientation and structure of ZnO nanorods are investigated. The Al-doping ratios are 0%, 0.2%, 0.8% and 2%. The Aluminum Nitrate Nonahydrate (Al (NO3)3.9H2O) was added to the growth solution, which is used as a source of the aluminum dopant element. The morphology and structure of the Al-doped ZnO nanorods are characterized by field emission scanning electron microscopy (FESEM) and high-resolution X-ray diffractometer (XRD). using the radio RF (Radio frequency) magnetron technique. Results and Discussion: The results show that the Al-doping have remarkable effects on the topography parameters such as diameter, distribution, alignment, density and nanostructure shape of the ZnO nanorods. These topography parameters have proportionally effective with increases of the Al-doping ratio. Also, X-ray diffraction results show that the Al-doping ratio has a good playing role on the nanostructure orientation of the ZnO nanorods. Conclusions: The Aluminum Nitride Nanohydrate considered as a good Aluminum source for doping ZnONR. It is clear from FESEM results that the Al-doping of ZnONR has a remarkable effect on the surface topography of nanorods for all aluminum doping ratios. From XRD patterns, it concludes that as the Al-doping ratio increases, the reorientation of the nanostructure of ZnO increases towards [100] direction. The results obtained also have shown that the average diameter of a nanorod is increased with increasing the ratio of Al-doping.
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Cho, Hwiwon, Guy Vereecke, Karine Kenis, Tae-Gon Kim, Jin-Goo Park, Kurt Wostyn i Efrain Altamirano Sanchez. "Effect of pH and Ion Concentration on Wetting of Nanoholes and Water Structuring". ECS Meeting Abstracts MA2022-01, nr 28 (7.07.2022): 1253. http://dx.doi.org/10.1149/ma2022-01281253mtgabs.
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Like supervias in the back end of line, and deep contact holes with an aspect ratio higher than sixty in 3D-NAND memory, higher aspect ratio patterning is one of the important issue in advanced semiconductor manufacturing. As with the difficulty of patterning, the technique of cleaning the nanostructure so that it does not affect the next process is also considered important. In semiconductor cleaning, chemicals such as HF and NH4OH that include reactant ions are used for cleaning the semiconductor surface. Ions in bulk aqueous solutions were shown either as structure making or breaking effects in Marcus’s study (Chem. Rev., 2009). The classification of ions as structure making or breaking was confirmed using 1 M solutions in nanotrenches (Vereecke, Micro. Eng., 2021). This shows there is an ion effect, and it can change properties between solution and material surface. The addition of structure breaking ions in HF solutions was used to decrease the etch rate of oxide between fins (Vereecke, Micro. Eng., 2022). Going further from Marcus’s study, we focused on pH and ion concentration in the addition of structure making ions. In the nanostructure, it was considered necessary to study because the surface properties may vary depending on the degree of structuring and the influence of the zeta potential depending on the concentration and pH of the ions. In this work, we used an in-situ ATR-FTIR (Attenuated Total Reflection – Fourier Transformed Infra-Red) spectroscopy technique (Nicolet iS50 AEM, Thermo Fisher Scientific, USA) to characterize the wetting of nanostructures embedded in a silica matrix by UPW (Ultra-Pure Water) and electrolyte solutions, and a streaming zeta potential analyzer (SURPASS3, Anton Paar, Austria) to characterize the surface potential of flat surfaces of the same material. Wetting in the nanostructures was characterized by an analysis of the ratio of the OH stretching peak to OH bending peak (Vrancken, Langmuir, 2016). Also, dissolution of CO2 in the wetted nanostructures was monitored to compare the solubility and diffusivity in the nano-confined solutions with that in bulk solutions. In this experiment, we used dense arrays of silicon nanoholes in a PEALD SiO2 matrix (depth of about 300 nm, diameter of about 20 nm, and pitch 90 nm) that were fabricated on Si wafers using arrays of nanostructures, as described in Vereecke (2021). Crystal drying, wetting with a solution, and applying CO2 were performed in this order. HI, HBr, HCl were used for chemicals and pH 1, 2, 3, 4 was used for pH. Monitoring of the OH stretching to bending ratio showed little improvement in wetting as a function of pH between 1 to 4 as compared to UPW. Also, little difference was observed when changing the acid from HCl to HBr and HI, with anions of higher structure breaking properties according to Marcus (Chem. Rev., 2009). A higher CO2 solubility and a lower CO2 diffusivity were measured in the nanoconfined solutions as compared to bulk UPW, indicative of water structuring. A higher CO2 solubility at pHs 2-3 as opposed to pH 1 and 4 may originate from the proximity to the isoelectric point. Results will be complemented with tests performed at the isoelectric point and pH 0, with 1 M solutions where structure breaking properties of the used anions are expected to be stronger and wetting might be improved.
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Morales, A. Escobedo, U. Pal i M. Herrera Zaldivar. "Incorporation of Sb in ZnO Nanostructures Through Hydrothermal Process". Journal of Nanoscience and Nanotechnology 8, nr 12 (1.12.2008): 6551–57. http://dx.doi.org/10.1166/jnn.2008.18424.
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Incorporation of dopants in optoelectronic semiconductor nanostructures has been a matter of great interest in recent times. While such doping has been performed almost routinely using physical methods, use of low-cost chemical techniques for that purpose is still rare. We incorporated antimony in zinc oxide (ZnO) nanostructures through a low temperature hydrothermal method. In as-grown nanostructures, antimony remains partially in Sb2O3 phase. On thermal annealing at 500 °C, it dissociates and antimony incorporates into ZnO mainly by substituting zinc from the crystal lattice. Incorporation of Sb drastically modifies the morphology of the ZnO nanostructures. While incorporation of Sb in low concentration promotes the formation of uniform prismatic ZnO nanorods probably due to catalytic effect, high concentration of Sb causes the formation of rounded shaped nanoparticles due to high interfacial compressive stress. Incorporated Sb in the ZnO nanostructures remains inhomogeneously distributed. The optical band gap of the ZnO nanostructures increases a bit for lightly doped samples but it decreases for heavy doping.
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Kim, Honggyu, Yifei Meng, Ji-Hwan Kwon, Jean-Luc Rouviére i Jian Min Zuo. "Determination of atomic vacancies in InAs/GaSb strained-layer superlattices by atomic strain". IUCrJ 5, nr 1 (1.01.2018): 67–72. http://dx.doi.org/10.1107/s2052252517016219.
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Determining vacancy in complex crystals or nanostructures represents an outstanding crystallographic problem that has a large impact on technology, especially for semiconductors, where vacancies introduce defect levels and modify the electronic structure. However, vacancy is hard to locate and its structure is difficult to probe experimentally. Reported here are atomic vacancies in the InAs/GaSb strained-layer superlattice (SLS) determined by atomic-resolution strain mapping at picometre precision. It is shown that cation and anion vacancies in the InAs/GaSb SLS give rise to local lattice relaxations, especially the nearest atoms, which can be detected using a statistical method and confirmed by simulation. The ability to map vacancy defect-induced strain and identify its location represents significant progress in the study of vacancy defects in compound semiconductors.
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Gerdes, Frauke, Eugen Klein, Sascha Kull, Mohammad Mehdi Ramin Moayed, Rostyslav Lesyuk i Christian Klinke. "Halogens in the Synthesis of Colloidal Semiconductor Nanocrystals". Zeitschrift für Physikalische Chemie 232, nr 9-11 (28.08.2018): 1267–80. http://dx.doi.org/10.1515/zpch-2018-1164.
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Abstract In this review, we highlight the role of halogenated compounds in the colloidal synthesis of nanostructured semiconductors. Halogen-containing metallic salts used as precursors and halogenated hydrocarbons used as ligands allow stabilizing different shapes and crystal phases, and enable the formation of colloidal systems with different dimensionality. We summarize recent reports on the tremendous influence of these compounds on the physical properties of nanocrystals, like field-effect mobility and solar cell performance and outline main analytical methods for the nanocrystal surface control.
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Rashad, Shimaa, A. H. Zaki i A. A. Farghali. "Morphological effect of titanate nanostructures on the photocatalytic degradation of crystal violet". Nanomaterials and Nanotechnology 9 (1.01.2019): 184798041882177. http://dx.doi.org/10.1177/1847980418821778.
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The heterogeneous photocatalysis using semiconductor nanocrystals is an important process in the field of water treatment since it is a low cost, environmentally friendly, and zero waste technique. In this work, titanate nanostructures (sheets, tubes, and wires) were prepared by simple hydrothermal method. All samples were characterized by X-ray diffraction, transmission electron microscopy, Brunauer–Emmett–Teller surface area analysis, and Zetasizer. The results revealed that tuning the morphology of TiO2 changed the activity of the prepared nanostructures, where titanate nanowires exhibited the highest photocatalytic activity toward crystal violet dye, reaching 100% at pH 3 under ultraviolet illumination for 35 min.
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Yang, Peidong. "The Chemistry and Physics of Semiconductor Nanowires". MRS Bulletin 30, nr 2 (luty 2005): 85–91. http://dx.doi.org/10.1557/mrs2005.26.
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AbstractThe following article is based on the Outstanding Young Investigator Award presentation given by Peidong Yang of the University of California, Berkeley, on April 14, 2004, at the Materials Research Society Spring Meeting in San Francisco.Yang was cited for “innovative synthesis of a broad range of nanowires and nanowireheterostructure materials, and the discovery of optically induced lasing in individual nanowire devices.” One-dimensional nanostructures are of both fundamental and technological interest.They not only exhibit interesting electronic and optical properties associated with their low dimensionality and the quantum confinement effect, but they also represent critical components in potential nanoscale devices. In this article, the vapor–liquid–solid crystal growth mechanism will be briefly introduced for the general synthesis of nanowires of different compositions, sizes, and orientation. Unique properties, including light-emission and thermoelectricity, will be discussed. In addition to the recent extensive studies on “single-component” nanowires, of increasing importance is incorporating different interfaces and controlling doping profiles within individual single-crystalline nanowires. Epitaxial growth plays a significant role in fabricating such nanowire heterostructures. Recent research on superlattice nanowires and other nanostructures with horizontal junctions will be presented. The implication of these heterojunction nanowires in light-emission and energy conversion will be discussed. Ways to assemble these one-dimensional nanostructures will also be presented.
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Huang, She Song, Zhi Chuan Niu i Jian Bai Xia. "Self-Assembled GaAs Quantum Rings by MBE Droplet Epitaxy". Solid State Phenomena 121-123 (marzec 2007): 541–44. http://dx.doi.org/10.4028/www.scientific.net/ssp.121-123.541.
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Fabrication of semiconductor nanostructures such as quantum dots (QDs), quantum rings (QRs) has been considered as the important step for realization of solid state quantum information devices, including QDs single photon emission source, QRs single electron memory unit, etc. To fabricate GaAs quantum rings, we use Molecular Beam Epitaxy (MBE) droplet technique in this report. In this droplet technique, Gallium (Ga) molecular beams are supplied initially without Arsenic (As) ambience, forming droplet-like nano-clusters of Ga atoms on the substrate, then the Arsenic beams are supplied to crystallize the Ga droplets into GaAs crystals. Because the morphologies and dimensions of the GaAs crystal are governed by the interplay between the surface migration of Ga and As adatoms and their crystallization, the shape of the GaAs crystals can be modified into rings, and the size and density can be controlled by varying the growth temperatures and As/Ga flux beam equivalent pressures(BEPs). It has been shown by Atomic force microscope (AFM) measurements that GaAs single rings, concentric double rings and coupled double rings are grown successfully at typical growth temperatures of 200°C to 300°C under As flux (BEP) of about 1.0×10-6 Torr. The diameter of GaAs rings is about 30-50 nm and thickness several nm.
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Yuwono, Akhmad Herman, Amalia Sholehah, Sri Harjanto, Donanta Dhaneswara i Fajrika Maulidiah. "Optimizing the Nanostructural Characteristics of Chemical Bath Deposition Derived ZnO Nanorods by Post-Hydrothermal Treatments". Advanced Materials Research 789 (wrzesień 2013): 132–37. http://dx.doi.org/10.4028/www.scientific.net/amr.789.132.
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Zinc oxide (ZnO) is an inorganic semiconductor material which has been widely studied due to its various potential applications. Over the past decades, one-dimensional (1-D) nanostructures such as nanowires and nanorods have stimulated significant scientific interests because of their unique properties in comparison to bulk materials. For the application of dye sensitized solar cell (DSSC), 1-D ZnO nanostructures are more desired than the spherical nanoparticles since the former provides ballistic effect leading to faster electron transfer which in turn can increase the device performance. Motivated by this consideration, in the current study ZnO nanorods were deposited on ITO glass substrate via chemical bath deposition (CBD) process where the seeding solution was prepared at 0°C. In order to increase their crystallinity and optical properties, the as-deposited ZnO nanorods were subjected to post-hydrothermal treatment at 150°C for 3, 6 and 9 hours. The scanning electron microscope (SEM) analysis revealed that the ZnO nanorods were successfully grown as vertically-aligned hexagonal structure, while the X-ray diffraction (XRD) study showed that the intensity of (002) crystal plane is the highest peak for all nanorod samples. The optical study by UV-Vis spectroscopy showed that the absorption edge of the as-deposited sample was slightly red-shifted to visible region after post-hydrothermal treatment. The ZnO nanorods sample derived from post-hydrothermal treatment for 6 hours provided the optimum nanostructural characteristics with an average diameter of 228 nm, crystallite size of 27.97 nm and the band gap energy,Eg, of 3.12 eV.