bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improvement of LDI BUMP Stripping Process by Development of Room Temperature PR Stripper
Authors: Kang Young-Min , Bae Dong Chan , Kim Hyun-Joon , Kim Young- Nam , Kim Young Ho , Kim Tae Sung 
Published: April 2011

ABSTRACTBump process using gold bump led to many cleaning problems like polymer residues, metal and polyimide consumption after stripping process. First of all, stripping process of bump photoresist is one of the difficult technologies since thickness of PR pattern of bump is thicker than that of general metal line at least 100 times. We investigated the improvement of LDI BUMP stripping Process at 25 with new chemical. We found that the wettability may be improved when the additive was added to the chemical and it improves the stripping ability. It was found that new chemical was superior to commercial chemical in terms of chemical stability, removal efficiency of polymer residue and decrease in metal and polyimide consumption. Also, we could obtain removal mechanism of photoresist pattern by measured Raman equipment and enhancement of yield in mass production line of semiconductor.
A Study of Tungsten-Titanium Barriers in Silver Metallization
Authors: Bhagat Shekhar , Theodore N. D. , Alford T. L. 
Published: April 2011

ABSTRACTThis work investigated the viability of tungsten-titanium barrier layers for silver metallization. Reactive sputtered W-Ti was deposited on a Si wafer followed by an Ag thin film over layer. These samples were then annealed in vacuum at temperatures up to 700 °C. Characterization of these samples included using x-ray diffractometry, Rutherford backscattering spectrometry, scanning transmission microscopy, secondary ion mass spectroscopy, transmission electron microscopy, and four point probe analysis. The results indicated that the metal/diffusion barrier stack was stable up to 600 °C. Silicon started moving into the tungsten-titanium film at temperatures above 600 °C. Movement of Si resulted in local Si voiding. These results showed the promise of W-Ti as an effective barrier layer for silver metallization for process temperatures below 600 °C.
Potential of Ag Interconnect and Contact Metallization for Various Applications via Cu Additions
Authors: Han Hauk , Zoo Yeongseok , Mayer James W , Alford Terry L 
Published: April 2011

ABSTRACTThe thermal stability of Ag(Cu) alloy thin films on indium tin oxide (ITO) has been investigated and compared to that of pure Ag thin films on ITO. Atomic force microscopy and X-ray diffraction results of annealed films show differences in the evolution of surface morphology and texture with annealing. The presence of Cu atoms in the silver impacts the surface energy and surface diffusion. This results in Ag and Ag(Cu) alloy having very different surface morphology and crystallographic texture. The enhanced texture and thermal stability of the Ag(Cu) alloy constitute its potential use contact as material for MOSFET and for flip-chip light-emitting diodes.
Formation of Ge Nanocrystals in Lu2O3 High-k Dielectric and its Application in Non-Volatile Memory Device
Authors: Chan Mei Yin , Lee Pooi See , Ho Vincent 
Published: April 2011

AbstractA simple technique for the formation of Ge nanocrystals embedded in amorphous Lu2O3 high-k dielectric was demonstrated by pulsed laser ablation followed by rapid thermal annealing in N2 ambient. The structure and composition of the Ge nanocrystals in the oxide matrix have been studied by transmission electron microscopy (TEM) and x-ray photoelectron spectroscopy (XPS) analysis. A significant change in the structure and chemical composition of the film was obtained upon annealing. Cross-sectional and plan-view TEM images confirmed the formation of small Ge nanocrystals in amorphous Lu2O3 matrix with a mean size of about 6nm in diameter and a high areal density of 7 × 1011cm−2. The nanocrystals are well-isolated by the amorphous Lu2O3 in between, with almost spherical shape which are favorable for non-volatile memory (NVM) application due to an effective charge confinement. XPS measurements on the as-deposited sample indicate the existence of Ge in its oxidized state, consisting of GeO2 and Ge suboxides. A spontaneous reduction of GeO2 and GeOx was obtained after the annealing treatment, which provides Ge nuclei for nanocrystal formation. It is found that a low annealing temperature of 400oC is sufficient to dissociate the GeO2 and GeOx leading to the formation of Ge nanocrystals. The application of the nanocrystals in NVM devices was demonstrated by C-V characterization of the memory capacitor devices fabricated with Al2O3 control oxide layer. C-V results show a significant effect of the structure and composition of the film on the electrical performance of the device. The annealed device exhibits good memory behavior with a large memory window of 1.2V achieved with a low operation voltage.
Memory Devices Based on Solid Electrolytes
Authors: Kozicki Michael N 
Published: April 2011

AbstractCurrent mainstream memory technologies are unlikely to completely fulfill the solid state data storage requirements that will be imposed beyond the 32 nm node of the International Technology Roadmap for Semiconductors. One potential replacement technology is resistance change memory based on solid electrolytes and a number of significant research and development efforts are already underway. The lowering of the resistance is attained by the reduction of ions in a relatively high resistivity electrolyte to form a conducting bridge between the electrodes. The resistance is returned to the high value via the application of a reverse bias that results in the breaking of the conducting pathway. Germanium chalcogenides and Ag-Ge-S ternaries in particular possess good thermal processing characteristics while maintaining the necessary high ion mobility for rapid switching. Thermally diffused copper in deposited SiO2 also is of interest, as thermal stability in excess of 600°C and commonly used constituents makes this material system compatible with the widest range of back-end-of-line processes. This paper details some of the developments in the understanding of the materials used in solid electrolyte resistance change devices and presents a short review of the electrical characteristics of devices based on Ag-Ge-S and Cu-Si-O electrolytes.
Recent Progress in Ferroelectric Random Access Memory Technology
Authors: Ishiwara Hiroshi , Ishiwara Hiroshi 
Published: April 2011

AbstractIn this paper, ferroelectric materials suitable for realizing high-density 1T1C-type (capacitor-type) FeRAM are first reviewed. It is found in BiFeO3(BFO) films formed by chemical solution deposition that leakage current density at a low electric field increases by substitution of Mn and Cr atoms for Fe atoms. But, it is also found that the breakdown characteristic is much improved by substitution of these atoms. Because of the better breakdown characteristic, the leakage current densities in the 3 and 5% Mn-substituted films are lower than that in an undoped BFO film at an applied electric field of 1MV/cm at room temperature, and thus well saturated hysteresis loops in P-E (polarization vs. electric field) characteristics are observed in these films.Next, recent technological progress in transistor-type FeRAM, in which data are stored in a single ferroelectric-gate FET(field effect transistor), is discussed. It is demonstrated that the data retention time of ferroelectric-gate FETs is much improved by use of HfO2-based buffer layers which are inserted between the ferroelectric film and Si substrate for preventing interdiffusion of constituent elements. Particular attention is paid to FETs with a Pt/SrBi2Ta2O9/HfO2/Si gate structure, in which the data retention time longer than 30 days has been attained. Finally, the cell structure and operation principle of 1T (one transistor)-type FeRAM are discussed.
Investigation of Magnetic Behaviour of Mechanical Activation Derived Multiferroic BiFeO3
Authors: Garg Ashish , Thota Hari Kishan , Pandey Brajesh , Verma H C 
Published: April 2011

AbstractHere we report on the synthesis of multiferroic BiFeO3 ceramics by mechanical activation and detailed investigation into its magnetic behavior. The mechanically milled ceramic was calcined at temperatures up to 800°C. X-ray diffraction studies show only the pure BiFeO3 phase forms at 700°C. Vibrating sample magnetometer (VSM) measurements were carried out up to 1.5 Tesla and the results show a weak magnetic ordering in the ceramics. The magnetic measurements were also done on the samples heat treated under various cooling conditions. VSM measurements showed pronounced effect of cooling on the Magnetization vs Field curves. Mössbauer measurements show that short range Fe2O3 ordering is still present in the sample that goes undetected by XRD. This component decreases as the calcination temperature is increased. The nature of magnetic ordering improves upon heating from 600 to 700°C, also suggested by pure BiFeO3 phase formation at 700°C. Magnetization vs Temperature measurements conducted on the sample heat treated at 700°C for 1hr followed by cooling in air show an antiferromagnetic transition at ∼370°C.
Sol-Gel Synthesis and Characterization of BiFeO3-PbTiO3 Thin Films
Authors: Garg Ashish , Kar Soumya , Dixit Anju , Agrawal D C 
Published: April 2011

AbstractIn this work, we report on the synthesis and characterization of thin films of (BiFeO3)1−x (PbTiO3)x (BFPT) solid solutions of compositions around morphotropic phase boundary (MPB) grown on platinized silicon (111) Pt/TiO2/SiO2/Si substrate by sol-gel based spin coating technique. The films were post-annealed at 700 and 750°C for 1 h in air. Morphological analysis of the films was carried out by scanning electron microscopy. Grazing incidence X-ray diffractometry revealed the perovskite structure of the films and peaks suggested the presence of rhombohedral structured pure BFPT phase in polycrystalline form. Scanning electron microscopy suggested that films annealed at 750degC had a denser microstructure as compared to those at 700°C. The room temperature dielectric constant of the films with composition of BF:PT :: 75:25 was measured to be ∼1200 at a frequency of 100 kHz.
Ge2Sb2Te5 Film Deposition and Properties
Authors: Ye Mengqi , Tao Rong , Ding Peijun , Bello Abner 
Published: April 2011

AbstractMagnetron sputter deposition of Ge2Sb2Te5 film is presented. Good thermal control of the wafer is found critical for maintaining process repeatability. In-situ wafer heating conditions have strong impact on as-deposited Ge2Sb2Te5 film properties such as resistivity, density, stress, composition, and microstructure. The effects of wafer bias and sputtering pressure are also discussed.
Room Temperature Growth of Indium Oxide Films by Reactive Ion Beam Assisted Deposition
Authors: Wang Kai , Vygranenko Yuriy , Nathan Arokia 
Published: April 2011

AbstractConducting and semiconducting indium oxide thin films have been grown at room temperature by oxygen ion beam assisted e-beam evaporation. We studied an influence of the deposition conditions on thin film properties including the crystal structure, resistivity, optical transmittance, stoichiometry, morphology, and intrinsic stress. X-ray diffraction analysis shows that the crystal structure of indium oxide films changes from amorphous to polycrystalline with preferred (222) orientation when the discharge current increases from 0.5 A to 2.0 A. Film resistivity is tailored in a wide range from 3E-4 ohm-cm to 2E9 ohm-cm by modifying both the evaporation rate of indium and the discharge current of the oxygen ion source. X-ray photoelectron spectroscopy data reveal that the highly-resistive films are more oxygen-enriched than the highly-conductive samples due to electrical activity of the oxygen vacancies. Morphological properties are evaluated using an optical profiler and a measured root-mean-square (RMS) roughness is ~1 nm for produced indium oxide films. All films being studied in this work have compressive stress ranging from 0.4 Gpa to 1.8 Gpa. They are highly transparent with a transmittance up to 90%.Thus, high-performance indium oxide films can be engineered by the reactive ion beam assisted deposition to meet the requirements of different applications such as solar cells, photodetectors, OLEDs, transparent TFTs, and optical coatings.
Copper-Indium-Boron-Diselenide Absorber Materials
Authors: Ianno Natale J. , Soukup Rodney J. , Santero Tobin , Kamler Chad , Huguenin-Love James , Darveau Scott A. , Olejnicek Jiri , Exstrom Christopher L. 
Published: April 2011

AbstractAttempts to fabricate new CuIn1-xBxSe2 (CIBS) and CuBSe2 (CBS) thin-film materials have been complicated by the formation of interfering crystallites and by the loss of boron from the magnetron sputtered precursor alloys during the selenization and annealing processes. Raman and Auger spectroscopic analysis as well as x-ray diffraction studies show that the formation of boron selenide may be contributing to the difficulty in creating these new materials.
Nano-scale Observation of Si Trench Sidewall Surface Morphology by AFM Technology
Authors: Hiruta Reiko , Kuribayashi Hitoshi , Shimizu Ryosuke 
Published: April 2011

AbstractWe have developed an atomic force microscopy (AFM) observation technique with which Si trench sidewall surface can be scanned with the tip of cantilever to investigate its nano-scale morphologies. By developing a new technique of cleaving the substrate at the center of a micron-sized trench along its longitudinal direction [011], the sidewall nano-scale morphology of the trench could be observed with the AFM technique. By comparing of cross sections of the images, we also investigated the difference between Si and carbon nanotube (CNT) tips for the AFM observations. According to the results, the CNT tip proved to show a superior signal-to-noise (S/N) ratio compared with the Si tip. The CNT tip enables us to observe the step patterns of the sidewalls of micron-sized trench structures in the various phases of hydrogen annealing.
Localized Ferromagnetic Resonance Force Microscopy of a Continuous Permalloy-Cobalt Film
Authors: Nazaretski Evgueni , Pelekhov Denis V. , Martin Ivar , Cha Kitty C. , Akhadov Elshan A. , Hammel P. Chris , Movshovich Roman 
Published: April 2011

AbstractWe report on the Magnetic Resonance Force Microscopy (MRFM) experiments performed on a 50 nm thick permalloy and a combined 20 nm thick permalloy – cobalt film. We studied the evolution of the MRFM spectra as a function of the vertical probe-sample distance and the lateral position as probe was scanned across the permalloy/cobalt interface. Our numerical simulations of the ferromagnetic resonance (FMR) modes excited in the presence of a non-uniform tip field of the cantilever compare well with experimental findings. This work demonstrates the capability of MRFM to perform local FMR spectroscopy of different materials in continuous ferromagnetic films.
Piezoelectric Poly(3-hydroxybutyrate)-Poly(lactic acid) Three Dimensional Scaffolds for Bone Tissue Engineering
Authors: Mendenhall Juana , Li Dapeng , Frey Margaret , Hinestroza Juan , Babalola Omotunde , Bonnasar Lawrence , Batt Carl A 
Published: April 2011

AbstractThree dimensional scaffolds (3D) are promising for future nanoscale materials and tissue engineering applications being that they have architecture and mechanical properties similar to natural tissue. In this work, poly(lactic acid) fibers were prepared via electrospinnig with average diameters of 2580 nm. Using Enzymatic Surface-Initiated polymerization (ESIP), poly(3-hydroxybutyrate) were coated on poly(lactic acid) fibers. This provides an alternative method to enzymatic surface modification of fibers. ESIP of PHB produces a granular film providing surface topography and increases mechanical properties of PLA fibers alone. When using covalent approaches, PHB granules provide surface topography of 200-500 nm with a polydisperse coverage area. Compressive modulus measurements of PLA and PHB/PLA scaffolds were 25 kPa and 73 kPa, respectively. The percent crystallinity of PLA and PHB/PLA scaffolds was 17% and 30%, respectively. This rough topography, in addition to the crystallinity of the scaffold, facilitates Soas-2 osteoblast cell attachment. We have observed attachment of the osteoblast cells along the length of the oriented PLA and PHB/PLA composite scaffolds with different morphologies, rounded and stretched, throughout a depth of 90 µm.
Single Asperity Wear and Stress-Assisted Dissolution of Copper
Authors: Chua Bun H , Chandra Abhijit , Shrotriya Pranav 
Published: April 2011

AbstractThe focus of this paper is to investigate the synergistic influence of contact loads, surface stress state and chemical environment on material removal during mechanical stimulation of copper surface. A unique setup is used to generate well characterized stress states on a polished copper specimen. Stressed surface of copper specimen is stimulated using tip of the atomic force microscope (AFM) and material removed during stimulation is measured as a function of contact loads, surface stress state and chemical environment. Measured material removal rates display a complex dependence on contact pressures and in-plane stress state which changes as the pH of chemical environment changes from acidic to basic. A surface material removal mechanism based on a single asperity wear and stress-assisted dissolution is proposed to explain the experimental observations
Negative or Zero Thermal Expansion in Silicon Dicarbodiimide, Si(NCN)2
Authors: Kroll Peter , Yan Xuehua , Riedel Ralf , Ehrenberg Helmut 
Published: April 2011

AbstractUsing ab-initio molecular dynamics simulation we investigate the thermal expansion of β-Si(NCN)2 for temperatures up to 700 K. We find that the structure behaves isotropic, although its optimized ground state is tetragonal. Studying the zero-pressure volume as a function of temperature we find a negative expansion of the structure and a linear expansion coefficient αL of -2·10−5 K-1. We attribute this effect to a strong bending of the Si-N=C angle within the structure which increases on increasing the temperature. The stretching of Si-N and C=N bonds on the other side is regular.Experiments motivated by the computational study were carried out on nano-crystalline Si(NCN)2 powders. The XRD Mo Kα data shows a negative thermal expansion for β-Si(NCN)2 up to 600 K. Synchrotron data indicates zero expansion of β-Si(NCN)2 between 460K and 800 K.
Growth and Characterization of High-Performance GaN and AlxGa1−xN Ultraviolet Avalanche Photodiodes Grown on GaN Substrates
Authors: Dupuis Russell D. , Yoo Dongwon , Ryou Jae-Hyun , Zhang Yun , Shen Shyh-Chinag , Limb Jae , Yoder Paul D. , Hanser A. Drew , Preble Edward , Evans Keith 
Published: April 2011

AbstractWide-bandgap III-nitride-based avalanche photodiodes (APDs) are important for photodetectors operating in UV spectral region. For the growth of GaN-based heteroepitaxial layers on lattice-mismatched substrates such as sapphire and SiC, a high density of defects is introduced, thereby causing device failure by premature microplasma breakdown before the electric field reaches the level of the bulk avalanche breakdown field, which has hampered the development of III-nitride based APDs. In this study, we investigate the growth and characterization of GaN and AlGaN-based APDs on free-standing bulk GaN substrates. Epitaxial layers of GaN and AlxGa1−xN p-i-n ultraviolet avalanche photodiodes were grown by metalorganic chemical vapor deposition (MOCVD). Improved crystalline and structural quality of epitaxial layers was achieved by employing optimum growth parameters on low-dislocation-density bulk substrates in order to minimize the defect density in epitaxially grown materials. GaN and AlGaN APDs were fabricated into 30μm- and 50μm-diameter circular mesas and the electrical and optoelectronic characteristics were measured. APD epitaxial structure and device design, material growth optimization, material characterizations, device fabrication, and device performance characteristics are reported.
Superluminescence in Green Emission GaInN/GaN Quantum Well Structures under Pulsed Laser Excitation
Authors: Senawiratne Jayantha , Tomasulo Stephanie , Detchprohm Theeradetch , Zhu Mingwei , Li Yufeng , Zhao Wei , Xia Yong , Zhang Zihui , Persans Peter , Wetzel Christian 
Published: April 2011

AbstractWe report nonlinear optical investigation of green emission GaInN/GaN multi-quantum structures grown along c- and m-axes on sapphire and bulk GaN substrates, respectively. Under intense pulsed photo excitation, we observed strong superluminescence near the lasing condition in c-plane grown quantum well structures with full width at half maximum of 6 nm. The superluminescence couples out of the edge of the sample in a mode pattern consistent with gain in a high mode of the waveguide. The wavelength of the superluminescence is 474 nm. The threshold intensity of superluminescence was found to be 156 kW/cm2. Increasing pump intensity leads to a strong photoluminescence blueshift as large as 380 meV in samples grown along the c-axis on sapphire substrate, while under the same excitation conditions, the blue shift for the m-axis grown structure on bulk GaN substrate is less than 10 meV. The large emission blueshift is hereby attributed to the internal piezoelectric field in the c-axis grown structure. We observe a gain value of 20 cm-1 together with internal absorption losses of 2.3 – 6.0 cm-1 for the superluminescent samples.
Contact Characterizations of ZrN Thin Films Obtained by Reactive Sputtering
Authors: Pelleg Joshua , Bibi Asaf , Sinder Michael 
Published: April 2011

AbstractThe contact properties of ZrN on p-type Si obtained by magnetron reactive sputtering were investigated. Schottky diodes characteristics were evaluated by current-voltage (I-V) and capacitance voltage (C-V) measurements. The barrier heights obtained by I-V and C-V are in the range of 0.55-0.63V and 0.88-0.91V, respectively.
Magnetocaloric Effects of Binary Rare Earth Nitrides
Authors: Hirayama Yusuke , Nakagawa Takashi , Kusunose Takafumi , Yamamoto Takao A. 
Published: April 2011

AbstractWe synthesized HoxEr1−xN (x =0.1, 0.3, 0.5, 0.7, 0.9) by the carbothermic reduction method. The magnetic entropy change, ΔS, which is an indicator of performance of magnetocaloric effect, MCE, was obtained from data sets of magnetization M (H, T) measured at various temperature, T, and magnetic field, H, through the Maxwell equations. The Thus obtained ΔS vs. T curves have peaks at temperatures depending on x in a range of 8–18 K. ΔS values of HoxEr1−xN expressed in terms of J K−1 m−3 were higher than those of intermetallic compounds of rare earth and transition metals previously reported. These ΔS peak plots are along a convex curve, which may indicate an interaction between the two components.
NITRIDE BASED SCHOTTKY-BARRIER PHOTOVOLTAIC DEVICES
Authors: Jampana Balakrishnam R , Jani Omkar K , Yu Hongbo , Ferguson Ian T , McCandless Brian E , Hegedus Steven S , Opila Robert L , Honsberg Christiana B 
Published: April 2011

AbstractSchottky-barrier photovoltaic devices are fabricated by selective metal deposition on p-GaN. A 1.25 V open-circuit voltage is observed for the best device. Devices were optimized by annealing in forming gas at temperatures ranging from 550°C to 700°C. Annealing time and forming gas flow rate are used to control the metal-semiconductor Schottky barrier formation. Optimum fabrication parameters are achieved based on photovoltaic response from the devices under UV illumination. Barrier heights (0.47 eV - 0.49 eV) were used as basis to compare the device response. The Schottky-barrier height is very sensitive to processing conditions, for example a 2.5% increase in barrier height is observed when Schottky contact annealing temperature is changed from 600 °C to 650 °C. Under UV illumination, the open-circuit voltage and short-circuit current increase with increasing annealing temperature while the series resistance decreases under such conditions.