bluuebunny/crossref_metadata_2025_split huggingface dataset:
Paramagnetic Defects and Photoluminescence in Carbon Rich a-SiC:H Films: Role of Hydrogen and Excess of Carbon
Authors: Vasin A. V. , Konchits A.A. , Kolesnik S.P. , Rusavsky A.V. , Lysenko V.S. , Nazarov A.N. , Ishikawa Y. , Ashok S. 
Published: April 2011

AbstractThe effect of excess of carbon in a-Si1−xCx:H has been studied with regard to local structure reconstruction, evolution of paramagnetic defects and photoluminescence (PL) after vacuum annealing over the temperature range 300–850°C. Two series of samples with stoichiometric (Si0.5C0.5) and carbon-rich (Si0.3C0.7) compositions were studied by Electron Paramagnetic Resonance (EPR), Photoluminescence (PL) and Raman scattering. It is found that there exist two effects responsible for the PL efficiency of a-Si1-xCx:H films: “killing” effect of carbon-related paramagnetic defects and “enhancing” effect of carbon-hydrogen bonds in Si:C-Hn configuration. A microstructure model is proposed for explaining the non-monotonic behavior of integrated PL intensity and concentration of paramagnetic centers and Si:C-Hn bonds as a function of annealing temperature. This model evolves from the following principal processes during thermal treatment of a-Si1−xCx:H: thermally activated release of weakly bonded hydrogen, migration of hydrogen within material and interaction of hydrogen with carbon-related defects.
Application of Computational Intelligence to Investigation of Defect Centers in Semi-Insulating Materials by Photoinduced Transient Spectroscopy
Authors: Kaminski Pawel , Jankowski Stanislaw , Kozlowski Roman , Bedkowski Janusz 
Published: April 2011

AbstractA computational intelligence algorithm has been applied to extracting trap parameters from the photocurrent relaxation waveforms recorded at the temperature range of 20-320 K for semi-insulating (SI) InP samples. Using the inverse Laplace transform procedure, the spectral surfaces, visualized in the three dimensional space as functions of temperature and emission rate, are calculated. The processes of thermal emission of charge carriers from defect centers manifest themselves as the sharp folds on the spectral surface. Using a set of Gaussian functions, the approximating surface is created and the ridgelines of the folds, giving the temperature dependences of the emission rate for the detected traps, are determined. The approximation is performed using the support vector machine (SVM) algorithm which allows for trading off between the model complexity and fitting accuracy. The new approach is exemplified by comparing the defect structure of SI InP wafers after annealing in iron phosphide and pure phosphorous atmospheres.
Comparative Analysis of Process of Diffusion of Interstitial Oxygen Atoms and Interstitial Hydrogen Molecules in Silicon and Germanium Crystals: Quantumchemical Simulation
Authors: Gusakov Vasilii 
Published: April 2011

AbstractA theoretical modeling and comparative analysis of the process of diffusion of the interstitial oxygen atoms and interstitial hydrogen molecules (H2) in silicon and germanium crystals at normal and hydrostatic pressure (HP) have been performed. The process of diffusion of particle with a strong interaction with a crystal lattice (interstitial oxygen atom) is a cooperative process. Three nearest Si (Ge) atoms of crystal lattice are involved in an elementary oxygen jump from a bond-center site to another bond-center site along a path in the (110) plane. It is precisely their optimum position (corresponding to a local minimum of the crystal total energy) determines the value of the diffusion parameters of an interstitial oxygen atom in silicon and germanium crystals. In a sense, the diffusion process may be considered as a diffusion process of qwasiparticle – (Oi+3Si). In the case of a particle weakly interacting with a crystal lattice (interstitial hydrogen molecules) we come up against the opposite case – the diffusion of H2 is not a cooperative process. The calculated values of the activation energy and pre-exponential factor for an interstitial oxygen atom δE(Si) = 2.59 eV, δE(Ge) = 2.05 eV, D0 (Si)= 0.28 cm2 s−1, D0 (Ge)= 0.39 cm2 s−1 and interstitial hydrogen molecule δE(Si) = 0.79 – 0.83 eV, δE(Ge) = 0.58 – 0.62 eV D0 (Si)= 7.4 10−4 cm2 s−1, D0 (Ge)= 6.510−4 cm2 s−1 are in an excellent agreement with experimental ones and for the first time describe perfectly an experimental temperature dependence of an interstitial oxygen atom and hydrogen molecules diffusion constant in Si crystals.
Effect of Strain and Polarization Grading on Hole Transport across Tunneling Barriers between Metals and Wurtzite Indium Gallium Nitride
Authors: Praharaj Choudhury Jayant 
Published: April 2011

AbstractWe theoretically model the transport of holes across graded wurtzite Indium Gallium Nitride layers with large barriers to metals of the order of 2 electron volts. The effect of continuous strain grading and the resulting piezoelectric grading is explicitly taken into account. As data about critical thicknesses for dislocation creation are scarce for these materials, the grading widths considered for the calculations are deliberately kept small to ensure that the layers are below theoretically predicted critical thickness limits. The spatial variation of spontaneous and piezoelectric polarization creates bulk bound polarization charges that have a strong effect on the electrostatics of the layers, and creates the optimum conditions for efficient tunneling of holes. We also explicitly model the effect of the different hole masses for the valence band. Three orders of magnitude increase of tunneling intensity is seen for split-off holes with effective masses of 0.15 for the case of moderate grading from 30 % Indium to 0% Indium over 30 angstroms, compared to the case without grading. The case of very aggressive grading of the same change in composition over 10 angstroms does not lead to any extra benefits and leads to a decrease in tunneling intensity. The electric field for more aggressive grading dominates the electric field for the moderate grading both near the top and the bottom of the barrier. However, the effective barrier width at the valence band edge becomes higher for the case of aggressive grading, and most of the carriers see a damped tunneling amplitude.
Fabrication of Strain Relaxed Silicon-Germanium-on-Insulator (Si0.35Ge0.65OI) Wafers using Cyclical Thermal Oxidation and Annealing
Authors: Wang Grace Huiqi , Toh Eng-Huat , Tung Chih-Hang , Foo Yong-Lim , Tripathy S. , Lo Guo-Qiang , Samudra Ganesh , Yeo Yee-Chia 
Published: April 2011

AbstractA novel scheme for the fabrication of SiGe-on-insulator (SGOI) substrates comprising a thin and relaxed silicon-germanium (SiGe) layer with high Ge mole fraction is reported. A cyclical thermal oxidation and annealing (CTOA) process is introduced to alleviate issues associated with surface roughening and non-uniformity in Ge content. A systematic study of the stress developed in the SiGe layer as condensation takes place is presented. A clear understanding of the strain evolution enables the SGOI substrate fabrication to be tailored according to the requirements of strain engineering in high mobility MOSFETs.
Deep Level Transient Spectroscopy Study of Dislocations in SiGe/Si Heterostructures
Authors: Lu Jinggang , Park Yongkook , Rozgonyi George A 
Published: April 2011

AbstractExamination of dislocations in the as-grown and annealed SiGe/Si heterostructures by DLTS indicates the three strong DLTS bands from 70 to 270K in the as-grown sample are likely related to intrinsic point defects or dislocation trails. A small amount of Fe at dislocations dramatically increases their electrical activity, and the trap concentration due to Fe-decorated dislocations can well exceed the total Fe impurities presented along dislocations. Through examining the competitive trapping of Fe at boron and dislocations, it is suggested that Fe trapping only happens at disordered sites along dislocations, such as kinks.
Germanium Layer Exfoliation by Ion-Cut Processes
Authors: Job Reinhart , Düngen Wolfgang 
Published: April 2011

Abstract(100)–oriented Czochralski germanium (Cz Ge) wafers were implanted with hydrogen at en-ergies up to 100 keV (related to H+) at a doses of D = 4·106 H+/cm2. Post-hydrogen annealing in normal air atmosphere on a hotplate was employed for 10 min at various temperatures between 350 °C and 600 °C to investigate the samples with regard to blistering and layer exfoliation having in mind the Smart-Cut™ technology for GOI structure formation. The generation and evolution of blisters and craters (“exploded” blisters demonstrating layer exfoliation) were investigated in dependence on the annealing temperature by atomic force microscopy and μ-Raman spectroscopy. The latter method points out the appearance of strong tensile stress upon H+ implantation and subsequent annealing. If the tensile stress exceeds about 1.2 GPa layer exfoliation occurs.
Investigation of Biaxial Strain in Strained Silicon on Insulator (SSOI) Using High-Resolution X-ray Diffraction
Authors: Zoo Yeongseok , Theodore N. D. , Alford Terry L. 
Published: April 2011

AbstractIntrinsic biaxial strain values of strained Si on insulator (SSOI) layers were measured using symmetric Bragg-Brentano configuration (i.e., {004} θ-2θ scans) and asymmetric {224} rocking curves. We confirmed that the twist angle between the layer and substrate can be incorporated into the biaxial strain equations for epitaxial layers. Moreover, as the samples were annealed up to 1200°C, the tensile parallel strains increased from 0.56% to 0.7%. Since both the overlying strained Si and underlying substrate maintained a stressed state in the buried SiO2, the compressively strained oxide retained the lattice expansion of the overlying strained Si and resulted in the increasing parallel strains after annealing.
Sub 50nm Strained n-FETs Formed on Silicon-Germanium-on-Insulator Substrates and the Integration of Silicon Source/Drain Stressors
Authors: Wang Grace Huiqi , Toh Eng-Huat , Hoe Keat-Mun , Tripathy S. , Lo Guo-Qiang , Samudra Ganesh , Yeo Yee-Chia 
Published: April 2011

AbstractSilicon (Si) source and drain (S/D) regions have been successfully integrated in thin-body silicon-germanium-on-insulator (SGOI) n-FETs. The selectively grown Si S/D induces uniaxial tensile strain in the SiGe channel. Devices with gate length LG down to 50 nm were fabricated. The Si S/D gives rise to 40% higher saturation drive current IDsat for transistors fabricated on Si0.60Ge0.40-on-insulator substrates. For n-FETs fabricated on Si0.75Ge0.25-on-insulator substrates, a 27% IDsat enhancement was observed. Lattice mismatch between the silicon S/D region and the SiGe channel was exploited to induce lateral tensile strain and vertical compressive strain in the channel, leading to enhancement in electron mobility. Analyses of contributions from the tensile strain to mobility enhancement and performance improvement are discussed
Material and Electrical Characterization of Nickel Silicide-Carbon as Contact Metal to Silicon-Carbon Source and Drain Stressors
Authors: Lee Rinus Tek Po , Yang Li-Tao , Ang Kah-Wee , Liow Tsung-Yang , Tan Kian-Ming , Wong Andrew See-Weng , Samudra Ganesh S. , Chi Dong-Zhi , Yeo Yee-Chia 
Published: April 2011

AbstractIn this paper, the material and electrical characteristics of Nickel-Silicon-Carbon (NiSi:C) films were investigated for the first time to ascertain the compatibility of NiSi:C contacts to silicon-carbon (Si:C) source/drain stressors. The incorporation of 1 atomic percent of carbon was found to increase both the Ni2Si-to-NiSi and NiSi-to-NiSi2 transformation temperatures. Our results show that the incorporation of carbon stabilizes the interfacial and surface morphology of NiSi:C films. We speculate that the incorporated carbon segregates into the NiSi:C grain boundaries and suppresses film agglomeration and NiSi-to-NiSi2 phase transformation. X-ray diffraction analysis further revealed that the formed NiSi:C films possessed a preferred orientation. Current-voltage measurements for NiSi and NiSi:C n+/p junctions exhibit similar cumulative distribution for junction leakage indicating that carbon incorporation does not have a detrimental impact on the n+/p junction integrity. Our results suggest that NiSi:C is a suitable self-aligned contact metal silicide to n-channel MOSFETs with SiC S/D stressors in a similar manner to the way in which NiSiGe is used for p-channel MOSFETs with SiGe S/D stressors.
Effect of Oxidizer on Chemical Vapor Deposited Hafnium Oxide-Based Nanostructures and the Engineering of their Interfaces with Si(100)
Authors: Singh Manish K. , Katamreddy Rajesh , Takoudis Christos G. 
Published: April 2011

AbstractThin films of hafnium oxide were deposited on silicon substrates using tetrakis-diethylamino hafnium as precursor. Two different oxidizers: (a) ozone/oxygen mixture, and (b) dry oxygen were used for comparative study of the effect of different oxidizers on the deposited films. The deposition using dry oxygen was carried out in a cold-wall rapid thermal processing metalorganic chemical vapor deposition (MOCVD) reactor, whereas ozone/oxygen mixture was used in a cold-wall atomic layer deposition (ALD) reactor. Annealing studies were carried out at 600 and 800°C in high-purity argon at atmospheric pressure. X-ray photoelectron spectroscopy (XPS) analyses of as-deposited and annealed films were performed to study the HfO2/Si interface. The films deposited using these two different oxidizers appeared to be of comparable quality. Silicon oxide formation at the interface occurred after annealing at 600°C and it increased upon further annealing at 800 °C.
Magnetic and Electronic Properties of n-type (Al,Ga) co-doped Zn(Cu)O based Dilute Magnetic Semiconductors
Authors: Chakraborti Deepayan , Prater John T. , Narayan Jagdish 
Published: April 2011

AbstractSystematic studies on the epitaxial growth and the effect of n-type (Al,Ga) doping on the magnetic and electrical properties of 2.0 % Cu doped ZnO dilute magnetic semiconducting thin films deposited on c-plane sapphire single crystals by pulsed laser deposition are reported here. An decrease in more than 3 orders of magnitude in resistivity from 2×101 Ohm cm for the 2.0 % Cu doped ZnO to ~5×10-3 Ohm cm for Al and Ga codoped films is observed. This increase in conductivity does not show any effect on ferromagnetic ordering thus contradicting the claim of free carrier mediated exchange as being responsible for ferromagnetic ordering in these DMS systems. A bound magnetic polaron or F-center mediated exchange is a possible explanation for the origin of ferromagnetism in these ZnO based DMS thin films.
Transition Metal Doped ZnO for Spintronics
Authors: Pearton Stephen J. , Norton D. P. , Ivill M. P. , Hebard A. F. , Chen W. M. , Buyanova I. A. , Zavada J. M. 
Published: April 2011

AbstractZnO is a very promising material for spintronics applications, with many groups reporting room temperature ferromagnetism in films doped with transition metals during growth or by ion implantation. In films doped with Mn during PLD, we find an inverse correlation between magnetization and electron density as controlled by Sn doping. The saturation magnetization and coercivity of the implanted single-phase films were both strong functions of the initial anneal temperature, suggesting that carrier concentration alone cannot account for the magnetic properties of ZnO:Mn and factors such as crystalline quality and residual defects play a role. Plausible mechanisms for the ferromagnetism include the bound magnetic polaron model or exchange is mediated by carriers in a spin-spilt impurity band derived from extended donor orbitals. Spin-dependent phenomena in ZnO may lead to devices with new or enhanced functionality, such as polarized solid-state light sources and sensitive biological and chemical sensors.
Improvement of Turn-Off Characteristics in ZnOTFT's by Introducing Hydrogen During MOCVD Growth
Authors: Jo Jungyol , Seo Ogweon , Choi Hyoshik , Jun Chan Bong 
Published: April 2011

Advantages of ZnO:High Mobility < 10 cm2Vsec, enables larger pixel opening, safer operation compared to TFT-LCD based on amorphous Si.High current driving TFT, high speed data transfer.High optical transparency, direct, wide bandgap.Stable against water and oxygen, because already oxidized.
Influence of Thermal Treatment on YBa2Cu3O7-x Thick Films Prepared by Electrophoretic Deposition on Ni and Ag Substrates
Authors: Dusoulier Laurent , Denis Samuel , Dirickx Michel , Vanderbemden Philippe , Ausloos Marcel , Cloots Rudi , Vertruyen Bénédicte 
Published: April 2011

AbstractWe have studied the sintering parameters of YBa2Cu3O7-x (YBCO) coatings produced by electrophoretic deposition (EPD) on Ag and Ni substrates. The maximal sintering temperature is ∼ 930°C due to partial melting and chemical contamination for Ag and Ni substrates respectively. Increasing the sintering duration does not improve significantly the densification. When Ar sintering atmosphere is used, the coating density is strongly increased on Ag substrates while adhesion is poor on Ni substrates. The Ar-sintered YBCO coating deposited on planar Ag substrate displays a significant magnetic shielding effect for low frequency applied magnetic induction.
Critical Currents of Overdoped Co-evaporated YBCO Coated Conductors
Authors: Hänisch Jens , Storer Jonathan , Sheehan Chris , Coulter Yates , Matias Vladimir 
Published: April 2011

AbstractCoated conductor samples, prepared by reactive co-evaporation, are investigated with respect to the hole-doping dependence of the critical current density. The samples are annealed in an atmosphere of variable oxygen content after which critical currents, critical temperature and the c-axis lattice spacing are measured. The lattice spacing increases with decreasing oxygen content, consistent with literature data. These co-evaporated samples show hole overdoped behavior with respect to the maximum Tc. The achievable range of hole doping in these samples seems to depend on surface coverage. Both self-field and in-field Jc at 75.5 K have a maximum in the overdoped region but at less than maximum oxygen content. The reason for the overdoping of these samples is discussed briefly in terms of Y-Ba disorder.
Evaluation and Testing of Organometallic Precursor for Copper Direct-Write
Authors: Majumder Prodyut , Tiwari Manish , Megaridis Constantine , McAndrew James , Xu Mindi , Belot John , Takoudis Christos G 
Published: April 2011

ABSTRACTA capillary bridge printing technique has been used to deposit copper interconnects using homogeneous solutions of a Cu(II) precursor in a series of low boiling primary alcohols. The rheological properties of the solutions have been measured first to determine their printability. The as-printed lines with subsequent annealing at relatively low temperatures (∼200 °C), in order to evaporate the volatile solvents and facilitate dissociation of the precursor deposit, produced conducting interconnects. The precursor has been demonstrated to be self-reducing and requires no reducing environment (e.g. H2) thus making the interconnect formation easier. Moreover, successful decomposition of the precursor into metallic Cu at such low temperatures holds promise for applications involving flexible polymer substrates.
On-chip Detection of Chemiluminescent Biomolecules Using an Integrated Thin Film Silicon Photodiode
Authors: Pereira A. , Pimentel A. , Chu V. , Prazeres D. M. F. , Conde J. P. 
Published: April 2011

AbstractA hydrogenated amorphous silicon photodetector on a glass substrate is used for the integrated, real-time detection of chemiluminescent reactions in solution. The light emission at 425 nm resulting from the horseradish peroxidase-catalyzed oxidation of luminol is detected by a p-i-n amorphous silicon photodiode operated at zero bias. The limit of detection of the present device is in the range of nanomole of horseradish peroxidase per liter.
Dielectrophoretic Microfluidic Switching for Lab on a Chip Applications
Authors: Wang Lisen , Lee Abraham Philip 
Published: April 2011

AbstractDielectrophoresis switching with vertical microelectrodes in the side wall of microchannel have been designed, fabricated and tested. A set of interdigitated electrodes in the side wall of the microchannels is used for the generation of non-uniform electrical field to introduce DEP force to repel or attract beads/cells to the sidewalls. A countering DEP force is generated from another set of electrodes patterning on the opposing side walls. These DEP forces can be adjusted by the voltage and frequency applied. By manipulating the coupled DEP forces, the particles flowing through the microchannel can be positioned at different equilibrium points along the width direction and continue to flow into different outlets. The objects of interest can be switched to desired channel outlets in the flow with no need of any moving parts and the down-stream channel can be more than three outlets. Experimental results for switching cells to two outlets and polystyrene microbeads to five outlets have been achieved. The effect of the geometry and flow rate on the performance of the switching was studied and an analytical solution for the optimal design and operation of DEP electrode arrays has been derived from the proposed model.
High Performance Photo-curable Polymers and Oligomers Based on Novel Ring-opening Reactions of Oxetanes
Authors: Nishikubo Tadatomi , Kudo Hiroto 
Published: April 2011

AbstractWe found new reactionsof oxetanes with many reagents such as acyl chlorides, silyl chlorides, phosphonyl chlorides, alkyl chlorides, aryl esters, thio esters, phosphonic acids, carboxylic acids, thiols, and phenols using suitable quaternary onium salts or crown ether complexes as catalysts. More recently, we also found an anionic ring-opening polymerization of certain oxetane monomers such as (3-methyl-3-hydroxymethyl)oxetane and (3-ethyl-3-hydroxymethyl)oxetane, which have hydroxyl groups, catalyzed by potassium tert-butoxide and 18-crown-6-ether complex, and an anionic ring-opening alternating co-polymerization of oxetane monomers with cyclic carboxylic anhydrides. These reaction systems have also been applied to the synthesis of new functional polymers. In this article, we would like to introduce the application of these reaction systems for the synthesis of high performance new photo-curable polymers and oligomers containing pendant or terminal (meth)acryloyl groups.
Discovery and Development of OMNiMIPs: One MoNomer Molecularly Imprinted Polymers
Authors: Spivak David A. , Sibrian-Vazquez Martha , Houck Stephen 
Published: April 2011

AbstractThere is enormous potential for the analytical applications of molecularly imprinted polymers (MIPs); for example, the imprinted polymer sites can function as the molecular recognition element of sensors, immunoassays, and separation media. However, difficulties with formulation variables and the need for empirical optimization have inhibited the widespread use of MIPs by the general scientific community. While investigating new crosslinkers for molecular imprinting, we have recently discovered a much simpler approach to MIP formation which utilizes a single crosslinking monomer, NOBE (N, Obismethacryloyl ethanolamine) in addition to template, solvent and initiator (shown in Scheme 1). We have given this molecular imprinting method the acronym “OMNiMIPs” which stands for one monomer molecularly imprinted polymers. This new formulation eliminates variables such as choice of functional monomer (FM) and crosslinker (XL), the ratio of functional monomer to crosslinker (FM/XL), and the ratio of functional monomer to template which normally complicates MIP design. The affects of OMNiMIP performance variables toward molecular recognition indicate significant differences between these new materials and traditional MIPs formulated with ethyleneglycol dimethacrylate (EGDMA) and methacrylic acid (MAA). These differences and the utility of OMNiMIPs will be discussed.