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Articles 31 - 51 of 51
Full-Text Articles in Physical Sciences and Mathematics
Optical Properties Of Zno/(Zn, Mg)O Quantum Wells, Thierry Bretagnon
Optical Properties Of Zno/(Zn, Mg)O Quantum Wells, Thierry Bretagnon
Turkish Journal of Physics
This paper reviews the optical properties of ZnO/(Zn, Mg)O single quantum wells grown by molecular beam epitaxy. Both heteroepitaxial quantum well growth along the polar c-direction and homoepitaxial quantum well growth on the nonpolar M plane cases are considered. The optical properties of these quantum wells are investigated by using reflectance, continuous wave photoluminescence, and time-resolved photoluminescence spectroscopies. The quantum-confined Stark effect dominates the properties of the excitons for polar quantum wells. The magnitude of the internal electric field that is induced by both spontaneous and piezoelectric polarizations is determined by comparing the experimental results with a variational calculation of …
Zno-Based Nanostructures For Diluted Magnetic Semiconductor, Millaty Mustaqima, Chunli Liu
Zno-Based Nanostructures For Diluted Magnetic Semiconductor, Millaty Mustaqima, Chunli Liu
Turkish Journal of Physics
Since the prediction by Dietl et al. in the year 2000, extensive research activities have been focused on the ZnO-based diluted magnetic materials (DMSs). Earlier works were mainly performed using bulk or thin film materials with transition-metal doping, and diverse magnetic properties including ferromagnetism, paramagnetism, and diamagnetism have been reported. Identifying the dominant mechanism of the ferromagnetic ordering and realizing reproducible ferromagnetism above room temperature have been the main research issues, but a consensus is still lacking even today. Recently, reports on ZnO nanostructures with ferromagnetic behavior have been growing due to the novel properties brought about by the high …
The Influence Of Tio_2 Nanostructure Properties On The Performance Of Tio_2-Based Anodes In Lithium Ion Battery Applications, Xiang Liu, Qian Sun, Fangzhou Liu, Aleksandra B. Djurisic, Alan Man Ching Ng, Maohai Xie, Tom Wood, Juan Antonio Zapien, Changzhong Liao, Kaiming Shih
The Influence Of Tio_2 Nanostructure Properties On The Performance Of Tio_2-Based Anodes In Lithium Ion Battery Applications, Xiang Liu, Qian Sun, Fangzhou Liu, Aleksandra B. Djurisic, Alan Man Ching Ng, Maohai Xie, Tom Wood, Juan Antonio Zapien, Changzhong Liao, Kaiming Shih
Turkish Journal of Physics
We investigated the properties of 7 different titanium dioxide nanostructures with different crystal structures (3 anatase, 2 rutile, and 2 mixed anatase--rutile phase). Nanoparticle samples and mesoporous sphere samples were investigated. Even for the same crystal structure, significant variations in performance were observed for anatase titania samples, while 2 rutile samples exhibited similar performance inferior to anatase-based anodes. Mixed-phase samples also exhibited lower specific capacity compared to the best performing anatase samples, and in this case a significant difference in performance was observed between nanoparticles and mesoporous spheres.
Optical And Magnetic Properties Of (Er, F) Co-Doped Sno_2 Nanocrystals, Vinod Kumar, Sitharaman Uma, Rajamani Nagarajan
Optical And Magnetic Properties Of (Er, F) Co-Doped Sno_2 Nanocrystals, Vinod Kumar, Sitharaman Uma, Rajamani Nagarajan
Turkish Journal of Physics
Uniformly (Er, F) co-doped SnO_2 nanocrystals, obtained by a low-temperature solution-based method, were characterized by a variety of analytical techniques. The structure, morphology, and ratio of the elements were confirmed by PXRD, SEM, and TEM analysis, respectively. From XPS analysis, atomic concentrations of Sn, O, and F were quantified. Interparticle pore size increased significantly (with a mean pore diameter of 25.82 nm) in the co-doped sample. Higher in-plane oxygen vacancies and bands due to multiphonon scattering were observed in the Raman spectrum of the sample. The defect traps in the sample were experimentally determined using TL spectroscopy. A broad intense …
Processing Of Germanium For Integrated Circuits, Ray Duffy, Maryam Shayesteh, Ran Yu
Processing Of Germanium For Integrated Circuits, Ray Duffy, Maryam Shayesteh, Ran Yu
Turkish Journal of Physics
In this review paper the authors will focus on Ge processing for integrated circuits. The key areas that require the most attention are substrates and integration, gate dielectrics, and access resistance. We will discuss each of these topics in turn, while also reviewing the most scaled Ge field-effect-transistor devices, and consider how modelling activities have matured for Ge in recent years.
Two-Dimensional Mos_2 As A New Material For Electronic Devices, Natalia Izyumskaya, Denis O. Demchenko, Vitaliy Avrutin, Ümi̇t Özgür, Hadis Morkoç
Two-Dimensional Mos_2 As A New Material For Electronic Devices, Natalia Izyumskaya, Denis O. Demchenko, Vitaliy Avrutin, Ümi̇t Özgür, Hadis Morkoç
Turkish Journal of Physics
We overview fundamental properties, preparation techniques, and potential device applications of single- and few-monolayer-thick molybdenum disulfide MoS_2 belonging to a new emerging class of materials: 2-dimensional semiconductors. To a large extent, the interest in the 2-dimensional materials is fueled by the quest for alternatives to graphene, which is hardly suitable for electronic devices because of the lack of a band gap. A unique combination of physical properties, including flexibility, high electron mobility, and optical transparency combined with a large band gap tunable from indirect 1.2 eV for bulk to direct 1.9 eV for a monolayer, make MoS_2 attractive for a …
Recent Advances In Organic Field Effect Transistors, Özge Abanoz, Christos Dimitrakopoulos
Recent Advances In Organic Field Effect Transistors, Özge Abanoz, Christos Dimitrakopoulos
Turkish Journal of Physics
We review the progress in the performance of organic field effect transistors that has been reported in the last 30 years, with a major emphasis on the last 10 years. We focus on the best performing organic semiconductors, and elucidate the underlying relations between the chemical and physical structures of the materials in the solid state and their electronic properties.
Soret And Dufour Effects On An Mhd Free Convective Flow Through A Channel Bounded By A Long Wavy Wall And A Parallel Flat Wall, Nazibuddin Ahmed, Kalpana Sarma, Hiren Deka
Soret And Dufour Effects On An Mhd Free Convective Flow Through A Channel Bounded By A Long Wavy Wall And A Parallel Flat Wall, Nazibuddin Ahmed, Kalpana Sarma, Hiren Deka
Turkish Journal of Physics
This paper presents Soret and Dufour effects on a 2-dimensional free convective magnetohydrodynamic (MHD) flow of a viscous incompressible and electrically conducting fluid through a channel bounded by a long vertical wavy wall and a parallel flat wall. A uniform magnetic field is assumed to be applied perpendicular to the flat wall. Governing equations of the fluid flow and heat and mass transfer are solved analytically subject to the relevant boundary conditions. It is assumed that the solution consists of 2 parts, a mean part and a perturbed part. The long wave approximation has been used to obtain the solution …
Deposition And Characterization Of Pbo--Pbs Multilayer Thin Films By Solution Growth Technique, Dominic Eya
Deposition And Characterization Of Pbo--Pbs Multilayer Thin Films By Solution Growth Technique, Dominic Eya
Turkish Journal of Physics
PbO-PbS thin films were deposited on glass substrates using the chemical bath deposition (CBD) technique. PbO thin films were deposited from the solution of lead nitrate (Pb(NO_3)_2) and sodium hydroxide (NaOH). Ethylenediaminetetraacetate (EDTA) served as the complexing agent. Some of the PbO films were used as substrate for the deposition of PbS. The PbS was deposited from alkaline solution of lead nitrate and thioacetamide. Triethanolamine was used as the complexing agent. Some of the films were subjected to thermal treatment after deposition. Energy dispersive X-ray fluorescence analysis confirmed the presence of Pb and S in the PbS thin films, while …
Quantum Chemical Calculations Of The Polymorphic Phase Transition Temperatures Of Zns, Znse, And Znte Crystals, Raşi̇t Ahiska, Dmytro Freik, Taras Parashchuk, Igor Gorichok
Quantum Chemical Calculations Of The Polymorphic Phase Transition Temperatures Of Zns, Znse, And Znte Crystals, Raşi̇t Ahiska, Dmytro Freik, Taras Parashchuk, Igor Gorichok
Turkish Journal of Physics
Molecular models of polymorphs modifications of zinc chalcogenides have been designed. Based on the results of ab initio quantum chemical calculations of the crystal structure of clusters the temperature dependences of the Gibbs energy of sphalerite and of wurtzite have been found. Phase transformations \"sphalerite-wurtzite\" temperatures have been evaluated.
Photovoltaic Enhancement Of Si Micro- And Nanostructure Solar Cells Via Ultrafast Laser Texturing, Falah A. H. Mutlak
Photovoltaic Enhancement Of Si Micro- And Nanostructure Solar Cells Via Ultrafast Laser Texturing, Falah A. H. Mutlak
Turkish Journal of Physics
The purpose of the present study was to achieve laser-microtextured Si structures, the material used as silicon wafers, with a thickness of 330 mu m for a fast laser texturing technique, in order to produce micro-/nanosurface textures by means of a UV femtosecond laser. A textured silicon surface was prepared that has the capability to trap light, thereby greatly reducing the visible light reflection for photovoltaic cells. The textured surface was measured by scanning electron microscope. The results showed a photocurrent increase of about 25% in the laser-textured zones.
Structural, Physical, And Electrical Properties Of Boro-Vanadate-Iron Glasses Doped With K_2o Alkali, Harshvadan R. Panchal
Structural, Physical, And Electrical Properties Of Boro-Vanadate-Iron Glasses Doped With K_2o Alkali, Harshvadan R. Panchal
Turkish Journal of Physics
The structural, physical, and electrical properties of semiconducting oxide glasses with composition xK_2O: (95-X) [B_2O_3: 2V_2O_5]: 5Fe_2O_3 (0 \le x \le 30) have been studied. The glasses were prepared by splat-quenching method. Fourier transform infrared spectroscopy (FTIR) studies of these glasses were carried out to study the effect of the modifier and glass former in the glasses. These changes in the molecular structure, bond length, and vibrational group were studied in the spectral range of 400-1350 cm^{-1}. The increase in the intensity and shifting of vibrational bands occurred towards lower wave numbers at 1400-1350 cm^{-1}, 1200 cm^{-1}, and 100-940 cm^{-1}. …
Neutron-Rich ^{208}Pb Nucleus With Delta Excitation Under Compression, Mohammed Hassen Eid Abu-Sei'leek
Neutron-Rich ^{208}Pb Nucleus With Delta Excitation Under Compression, Mohammed Hassen Eid Abu-Sei'leek
Turkish Journal of Physics
The spherical Hartree-Fock approximation is applied to a no-core shell model with a realistic effective baryon-baryon interaction. The ground state properties of a heavy spherical neutron-rich doubly magic ^{208}Pb nucleus under compression are investigated. It is found that the nucleus becomes more bound with the occurrence of Delta resonances. The creation of Delta increases as the compression is continuous. There is a considerable reduction in the compressibility when the Delta degree of freedom is activated. It is found that the Delta particle is the basic component of the ^{208}Pb nucleus besides nucleons at the ground state without any compression. When …
Uv-Vis And Xrd Investigation Of Graphite-Doped Poly(Acrylic) Acid Membranes, Mihai Todica, Traian Stefan, Simion Simon, Istvan Balasz, Liviu Daraban
Uv-Vis And Xrd Investigation Of Graphite-Doped Poly(Acrylic) Acid Membranes, Mihai Todica, Traian Stefan, Simion Simon, Istvan Balasz, Liviu Daraban
Turkish Journal of Physics
Possible modification of the structure of poly(acrylic) acid (PAA) membranes doped with graphite was investigated by UV-Vis and XRD techniques. The pure PAA membranes were characterized by good transparency in the domain 250-700 nm, with maximum absorption at 207 nm. The absorbance of membranes increased significantly after doping with graphite. The XRD patterns of pure membranes showed a low degree of order of the polymeric matrix. Some modifications of the parameters of the ordered domains of the polymer and of the graphite appeared at high concentrations of the dopant.
Saga Of Efficiency Degradation At High Injection In Ingan Light Emitting Diodes, Vitaliy Avrutin, Shopan A. Hafiz, Fan Zhang, Ümi̇t Özgür, Enrico Bellotti, Francesco Bertazzi, Michele Goano, Arvydas Matulionis, Adam T. Roberts, Henry O. Everitt, Hadis Morkoç
Saga Of Efficiency Degradation At High Injection In Ingan Light Emitting Diodes, Vitaliy Avrutin, Shopan A. Hafiz, Fan Zhang, Ümi̇t Özgür, Enrico Bellotti, Francesco Bertazzi, Michele Goano, Arvydas Matulionis, Adam T. Roberts, Henry O. Everitt, Hadis Morkoç
Turkish Journal of Physics
No abstract provided.
Synthesis And Gas Sensor Applications Of Nanostructured Zno Grown At Low Temperatures, Oleg Lupan, Thierry Pauporte, Lee Chow
Synthesis And Gas Sensor Applications Of Nanostructured Zno Grown At Low Temperatures, Oleg Lupan, Thierry Pauporte, Lee Chow
Turkish Journal of Physics
ZnO nanoarchitecture-based nano- and microdevices came into the focus due to their multifunctional operation. In this work, we summarize cost-effective procedures to grow ZnO nano- and microstructures, namely hydrothermal growth and electrochemical deposition. These techniques allow the controllable growth of ZnO nano- and microarchitectures at relatively low temperatures, below 100 °C, and do not require sophisticated equipment. We report on technological details for synthesis of ZnO and its characterization and applications in different novel devices such as gas sensors. Nanosensors and microsensors were fabricated using a focused ion beam and by metal welding an individual nano- and microstructure to form …
Fabrication And Characterization Of Green Light Emitting Diode, Shirin Siahjani, Matthew White, Niyazi Serdar Sariciftci, Şule Erten Ela
Fabrication And Characterization Of Green Light Emitting Diode, Shirin Siahjani, Matthew White, Niyazi Serdar Sariciftci, Şule Erten Ela
Turkish Journal of Physics
Phosphorescent polymer light emitting diodes (PLEDs) have been fabricated and characterized. A PLED was configured in an ITO/PEDOT:PSS/TPD:PBD:PVK:Ir(mppy)_3/LiF/Al device structure. Thicknesses of the active layer were optimized for an efficient phosphorescent organic light-emitting diode (OLED) device. The uniform mixing of the active layer was varied with different thicknesses. A hole transport layer of PEDOT:PSS was deposited in a thickness of 35 nm and an emissive layer of TPD:PBD:PVK:Ir(mppy)_3 was deposited in thicknesses of 90 nm, 56 nm, 40 nm, and 35 nm. The 56 nm thickness of the active layer was determined as the proper thickness according to results of …
Device Architectures In Organic Photovoltaics, James T. Mcleskey Jr
Device Architectures In Organic Photovoltaics, James T. Mcleskey Jr
Turkish Journal of Physics
The various device structures used in organic polymer solar cells are reviewed. The operating principles behind these devices are explained in order to provide the reasoning behind the different structures. The incorporation of nanostructures into both bilayer and bulk heterojunction devices to improve exciton separation, charge transport, and light absorption is discussed. Novel ideas such as electrospun fibers and supramolecules are also covered. Finally, the impact of these structures on overall efficiency is evaluated.
Amorphous And Micromorph Si Solar Cells: Current Status And Outlook, Vitaliy Avrutin, Natalia Izyumskaya, Hadis Morkoç
Amorphous And Micromorph Si Solar Cells: Current Status And Outlook, Vitaliy Avrutin, Natalia Izyumskaya, Hadis Morkoç
Turkish Journal of Physics
An overview of the current status and prospects of thin-film Si photovoltaics, including both hydrogenated amorphous and microcrystalline Si as well their combination known as micromorph solar cells, with a major focus on the technological development is given. Although thin-film Si solar cells have been one of the first commercially successful photovoltaic devices, today they face a tremendous challenge from variety of bulk Si technologies (mono- and multicrystalline Si) and compound-semiconductor thin-film solar cells, both of which have managed to substantially reduce the production cost and improve power conversion efficiency. Thin-film Si photovoltaics benefiting from the mighty mainstream Si industry …
Electron Field Emission From Nanostructured Semiconductors Under Photo Illumination, Oktay Yilmazoglu, Anatoli Evtukh, Shihab Al-Daffaie, Jens-Peter Biethan, Dimitris Pavlidis, Vladimir Litovchenko, Hans L. Hartnagel
Electron Field Emission From Nanostructured Semiconductors Under Photo Illumination, Oktay Yilmazoglu, Anatoli Evtukh, Shihab Al-Daffaie, Jens-Peter Biethan, Dimitris Pavlidis, Vladimir Litovchenko, Hans L. Hartnagel
Turkish Journal of Physics
New device concepts and materials for the fabrication of compact high-frequency vacuum sources and micro-nano-integrated X-ray sources are of particular interest for broadband communication, security screening of packages and chemical materials, biomedical examination, and other applications. This article integrates results on GaN- and ZnO-based nano and self-assembled structures. They were used as field emitter tips for cold electron emission at high local electric fields as well as for photoassisted field emitters to generate bunched electrons directly from the emitter tip. The results on functional field emitters as cold electron sources will be presented. They are key elements for building, among …
Nanosphere Lithography - Exploiting Self-Assembly On The Nanoscale For Sophisticated Nanostructure Fabrication, Eser Metin Akinoglu, Anthony John Morfa, Michael Giersig
Nanosphere Lithography - Exploiting Self-Assembly On The Nanoscale For Sophisticated Nanostructure Fabrication, Eser Metin Akinoglu, Anthony John Morfa, Michael Giersig
Turkish Journal of Physics
We demonstrate the fabrication of sophisticated nanostructures using nanosphere lithography (NSL). These include periodic triangular and pyramidal islands as well as periodically perforated thin films and cavities on the nano- and microscale. Furthermore, periodic arrays of vertically standing multiwalled carbon nanotubes are grown by plasma enhanced chemical vapor deposition from catalyst islands that were prepatterned by NSL. Moreover, we discuss the applicability of NSL to rough surfaces and show that the ratio between nanosphere size and roughness is determinant of the resulting nanostructure produced. Excellent, limited, and bad applicability of NSL are shown for smooth, rough, and very rough surfaces, …