bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of thermal annealing on the performance of polysilane based organic light emitting diode
Authors: Singh Ranbir , Katiyar Monica 
Published: April 2011

AbstractPolysilanes, being ó bonded, are promising materials for emission in ultraviolet/near ultraviolet (UV/NUV) region and exhibit adequate charge mobility for fabricating practical devices. This study contributes to the understanding of the effects of thermal annealing on the performance of organic light-emitting diodes (OLEDs) made of poly (n-butylphenyl-silane) (PS-4). OLEDs having indium tin oxide (ITO)/poly (3, 4-ethylenedioxythiophene) poly (styrenesulfonate) PEDOT: PSS/poly (n-butylphenylsilane) (PS-4)/lithium fluoride (LiF)/Al device structure were fabricated. PS-4 is spin coated and annealed for one hour at different temperatures (90-120°C). EL Spectra from these devices consists of white emission along with the UV peak. Current density-voltage (J-V), photoluminescence (PL) and electroluminescence (EL) spectra are also measured. White emission is significantly suppressed when PS-4 is annealed at higher temperature and threshold voltage is lowest at 110°C annealing temperature. This is correlated with PL emission and structural properties of PS-4 films. Surface morphology of PS-4 was measured using atomic force microscopy (AFM). The results are explained in terms of effect of annealing of polymer films on interchain interactions.
Low Mass Organic Semiconductor-polymer Dielectric Nanocomposites: Influence of the Guest-host Interactions on the OTFT Characteristics
Authors: Madec Marie-Beatrice , Crouch David J , Rincon-LLorente Gonzalo , Yeates Stephen G 
Published: April 2011

AbstractThe morphology and organic field effect transistor (OFETs) properties of two component blends of semicrystalline 6,13-bis(triisopropylsilylethinyl)pentacene (TIPS-pentacene) with selected amorphous and semi-crystalline low permittivity side chain aromatic insulating binders deposited at room temperature under vacuum from a good solvent are reported. When blended with an amorphous binder there is evidence from XPS for strong interaction between TIPS-pentacene and binder in the solidified film giving rise to twisted TIPS-pentacene crystals containing dislocations. Due to this strong interaction we see no evidence of segregation of TIPS-pentacene towards the active interface and hence we observe a rapid fall off in saturated hole mobility at a active concentration less than 50 wt-%. When blended with a crystalline binder there is no evidence from XPS of any interaction between TIPS-pentacene and binder in the solidified film. We propose that when a crystalline binder is used, which crystallizes more slowly from solution than TIPS-pentacene, we observe stratification of the active material to both interfaces and as a result an increase of saturated hole mobility to 0.4 cm2/Vs at 20 wt-% in isotactic poly(vinylbisphenyl). The potential application of the approach are in the formulation of low cost organic semiconductors whose solution and solid state properties can be fine tuned by careful binder selection.
Ionic Impurities in Poly(vinyl alcohol) Gate Dielectrics and Hysteresis Effects in Organic Field Effect Transistors
Authors: Egginger Martin , Irimia-Vladu Mihai , Schwödiauer Reinhard , Tanda Andreas , Bauer Siegfried , Sariciftci Serdar Niyazi 
Published: April 2011

AbstractPoly(vinyl alcohol) (PVA) is a water based dielectric often used as a coating layer in paper industry. Due to its water solubility PVA is also interesting as gate insulator in organic field effect transistors. Depending on the preparation of the PVA gate, transistors with and without hysteresis can be produced, with applications in organic electronic circuits or memory elements. In the production of PVA, a major side product is sodium acetate, an ionic salt not completely removed during industrial purification. Such ionic impurities likely influence the hysteresis in PVA based organic field effect transistors. While a hysteresis is desirable in memory elements it is unwanted in transistors for electronic circuits. Ways to prepare transistors with a desired transfer characteristic are described, for example by using electronic grade products directly from the purchaser of PVA, or by employing PVA purified by means of dialysis. Measurements are performed with metal-insulator-metal (MIM) structures and organic field effect transistors (OFETs), where Buckminsterfullerene C60 is employed as organic semiconductor.
High-mobility Organic Single-crystal Transistors with Amorphous Fluoropolymer Gate Insulators
Authors: Uno Mayumi , Tominari Yukihiro , Takeya Jun 
Published: April 2011

AbstractHigh-mobility rubrene single-crystal field-effect transistors are built on highly water- and oil-repellent fluoropolymer gate insulators. Roughness is intentionally introduced at the surface once to provide good adhesion to metal films and photoresist polymers for stable bottom electrodes. Before constructing interfaces with rubrene crystals, smoothness of the fluoropolymer surface is recovered by annealing at a moderate temperature to maximize mobility of the carriers induced near the interfaces. The estimated mobilities in the saturation region reproducibly exceeded 15 cm2/Vs for all the ten devices fabricated in this method and reach 30 cm2/Vs for the best two samples among them. The results demonstrate that the water-repellency and smoothness of the dielectric polymers are favorable in the excellent transistor performance.
Effect of Hot Band Annealing on Microstructure of Semi-Processed Non-Oriented Low Carbon Electrical Steels
Authors: Gutiérrez Emmanuel J. , Castañeda  , Rodriguez Armando Salinas 
Published: April 2011

ABSTRACTEffects of hot band annealing on the final microstructure and magnetic properties of cold rolled and annealed non-oriented grain Si-Al electrical steel strips are investigated. Microstructures are characterized using optical and scanning electron microscopy and magnetic properties are determined using a vibrating sample magnetometer. It is shown that annealing of hot rolled bands at temperatures between 800 and 850 °C causes rapid decarburization and development of a microstructure consisting of large columnar ferrite grains free of secondary particles. This microstructure leads, after cold rolling and a fast annealing treatment, to large grain microstructures similar to those observed in production scale, fully processed strips. It is observed that the final grain size increases with the final annealing temperature, leading to a significant improvement of the magnetic properties. Therefore, hot band annealing technology can be an attractive alternative processing route for the manufacture of non-oriented grain low carbon Si-Al processed electrical steel strips.
Quantitative Electronic Structure Analysis of α-AL203 Using Spatially Resolved Valence Electron Energy-Loss Spectra
Authors: MÜllejans Haral , Bruley J. , French R. H. , Morris P. A. 
Published: April 2011

ABSTRACTValence electron energy-loss (EEL) spectroscopy in a dedicated scanning transmission electron microscope (STEM) has been used to study the Σ11 grain boundary in α-A12O3 in comparison with bulk α-A12O3. The interband transition strength was derived by Kramers-Kronig analysis and the electronic structure followed from quantitative critical point (CP) modelling. Thereby differences in the acquired spectra were related quantitatively to differences in the electronic structure at the grain boundary. The band gap at the boundary was slightly reduced and the ionicity increased. This work demonstrates for the first time that quantitative analysis of spatially resolved (SR) valence EEL spectra is possible. This represents a new avenue to electronic structure information from localized structures.
Nanoindentation on Contamination-Free gold Films Using the Atomic Force Microscope
Authors: Schaefer D. M. , Reifenberger R. 
Published: April 2011

ABSTRACTNanoindentation experiments on high quality Au films were performed in vacuum using an atomic force microscope. In these experiments, elastic behavior was observed until loading forces greater than ∼ 20 nN were applied. For loads larger than this, systematic changes in the jump-to-contact, loading/unloading and lift-off regions of the data occur. These observations are consistent with a transition from elastic to inelastic behavior during indentation.
Observation and Measurement of Atomic Scale Imperfections in Materials Using CBED+EBI/H
Authors: Herring Rodney A. , Bonevich John E. , Tanji Takayoshi , Tonomura Akira 
Published: April 2011

ABSTRACTA new method of electron interferometry/holography (CBED+EBI/H) has been realized which produces interference between convergent beam electron diffracted beams. An electron biprism placed between the diffracted beams compensates for their diffraction angle by an induced potential. When overlaid the diffracted beams interfere to produce an interferogram. Holography is possible due to coherency of the electron beam. Reconstruction of the hologram by standard methods enables the phase change around the defects to be measured. These methods are very easy to apply and examples are given for small defects and defect clusters in heavy-ion implanted Si.
Direct Observation of Diffraction Arcs from Nanoscale Precipitates in Steels by Highly Brilliant and Focused Synchrotron Radiation Beam and Imaging Plate
Authors: Takagi Yasuo , Okitsu Yoshitaka , Ukena Toshiyasu 
Published: April 2011

ABSTRACTDirect observation of diffraction arcs by X-ray from nanoscale precipitates in steels has become possible for the first time by using a highly brilliant and focused synchrotron radiation beam at BL3A of Photon Factory, and also by using an “imaging plate”, a two dimensional X-ray detector which has a wide dynamic range and high sensitivity. For examples, most of the diffraction arcs from ε-Cu precipitates (∼200 Å in diameter and ∼1 at. % in concentration) in Cu-added steels were observed. The method can apply to nondestructive and in-situ observation of creation and growth processes of the precipitates which has close relationships to various physical properties of the matrix steels.
Photon Scanning Tunneling Microscopy of Optical Wavegnide Structures
Authors: Choo Ahn Goo , Chudgar Mona H. , Jackson Howard E , Brabander Gregory N. De , Kumar Mukesh , Boyd Joseph T. 
Published: April 2011

ABSTRACTPhoton scanning tunneling microscopy (PSTM) has been used to obtain effective refractive indices of optical channel waveguide structures. The local evanescent field intensity associated with the propagation modes of optical channel waveguides are measured at two different wavelengths. Both a tapered optical fiber tip and a semiconductor heterostructure tip are employed for detection. Local values of effective refractive index are measured for both TE and TM polarizations and compared to model calculations.
The Effect of Substrate Temperature on the Crystallinity and Stress of Ion Beam Sputtered Silicon on Various Substrates
Authors: Madras Cynthia G. , Goldman L. , Wong P.Y. , Miaoulis I.N. 
Published: April 2011

ABSTRACTAmorphous and polycrystalline silicon films are commonly used in a wide range of microelectronic and optical devices. Polycrystalline silicon is conventionally deposited by chemical vapor deposition (CVD) at temperatures in excess of 600°C. At these high deposition temperatures, thermal diffusion of dopants and thermally induced chemical reactions may occur within the substrate or device. Also, substrates with low melting temperatures such as germanium, may undergo irreversible deformation. In the present study, ion beam sputtering has been shown to enable the deposition of a stable polycrystalline silicon film on germanium as well as on silicon and glass substrates at temperatures as low as 350-400°C. The crystallization properties of silicon on the different substrate surfaces is reported. Crystallinity of the ion beam sputtered silicon films as a function of deposition temperature and substrate type is measured by X-Ray diffraction. These polysilicon films are shown to be thermally stable, have randomly oriented crystals, and have good adhesion to the substrates despite high compressive deposition stresses ranging from 700MPa to 1000MPa. Magnetron sputtered silicon films deposited on substrates in the same temperature range produced only completely amorphous films, with lower stresses and which are also thermally stable. This study demonstrated the feasibility of depositing extremely hard polycrystalline silicon films on germanium and other substrates by means of physical vapor deposition at temperatures as low as 350°C.
Profiling the Deep Trap Level in the Semiconductor Heterostructures by Small-Pulse Deep Level Transient Spectroscopy
Authors: Rong Zhang , Kai Yang , Guoyi Qing , Yi Shi , Shulin Gu , Hongbin Huang , Liqun Hu , Youdou Zheng , Duan Feng 
Published: April 2011

ABSTRACTIn this paper we report for the first time theoretical and experimental study on smallpulse DLTS measurements of deep levels in semiconductor heterostructures. A theoretical model has been developed on the basis of the Schodinger and Poisson's electrostatic equation. Distribution of charge density in the superlattice has been considered, especially transferred charges in the “narrow gap” sublayers. The calculated results indicate that tinder the 1017/cm3 doping condition, a 30mV small pulse corresponds to a 2nm “sampling space window”, it is enough to detect special signal of deep levels in each sublayer in the semiconductor heterostructures. A SiGe/Si sample has been measured by the small-pulse DLTS. The experimental results agree well with the theoretical prediction and show that the small-pulse DLTS is a good method to study deep levels in the semiconductor heterostructures.
Electromigration Properties and their Correlation to the Physical Characteristics of Multilevel Metallizations
Authors: Gadepally Kamesh , Geha Sam , Myers Edward R. , Thomas Michael E. 
Published: April 2011

ABSTRACTElectromigration lifetimes of multilayered metallizations of Al alloy (Al-0.5%Cu-l.0%Si) sandwiched with refractory metal films have been correlated to the interconnect microstructure and interactions with the underlying layer. In this study, Median Time to Failure (t50%, MTTF) data was obtained for multilayered Al alloy films by varying the Al deposition temperature from 200°C to 400° and the composition of the underlying substrate films. The Al alloys examined in this study were deposited over substrate films of sputtered Ti, reactively sputtered TiN and CVD TEOS deposited SiO2. All Al alloys were capped with a reactively sputtered TiN layer and covered with passivation.Physical characterization using TEM, XRD, SIMS, and AFM, was performed to determine the microstructural and chemical properties of the films and correlate them to the MTTF of the packaged interconnects. The role of material properties such as the grain size and interactions of the metallization with the underlying layers were found to substantially impact the electromigration lifetime.Based on data obtained from these studies, a number of interconnect metallization options will be discussed with respect to reliability and associated integration issues.
Microstructural Evolution of Aluminum Interconnects During Post-Pattern Anneals: Correlation to Improved Em Lifetime
Authors: Miner B. , Atakov E.A. , Shepela A. , Bill S. 
Published: April 2011

ABSTRACTThe number of Al triple point junctions (Ntp) correlates inversely to electromigration lifetimes for partially bamboo interconnects that fail by grain boundary (GB) diffusion. This work emphasizes the evolution of statistical microstructural parameters, Ntp and cluster length distribution, during post-pattern anneals. In addition to statistical measures, the structure of specific clusters before and after anneal is compared from TEM images of the same area of the same sample.Each post-pattern anneal lowers Ntp and shortens the length of individual polycrystalline segments, but with diminishing returns for subsequent anneals. With a TiN capping layer, the statistical microstructural improvement is less but the longest clusters, those most probable as failure sites, lose triple points during anneal. The distribution of cluster lengths is characteristic for a process.
Electromigration Failure in Thin Film Conductors Possessing a Near-Bamboo Structure
Authors: Lloyd J.R. 
Published: April 2011

ABSTRACTElectromigration failure in a near bamboo structure is investigated theoretically. Assuming that the diffusion path is interfacial, a flux divergence can be predicted based on the stress gradient induced by grain boundary electromigration in a sub Blech Length grain cluster. A possible explanation for the recently observed “trans-granular” voids is proposed.
Detailed Study of Electromigration Induced Damage in Al and AlCuSi Interconnects
Authors: Möckl U.E. , Bauer M. , Kraft O. , Sanchez J.E. , Arzt E. 
Published: April 2011

ABSTRACTBecause of the continuing miniaturization, electromigration (EM) phenomena are still a key issue in reliability of VLSI metallizations. The present study of EM induced voiding and hillocking was performed on unpassivated conductor lines with various widths and current densities. Stressed and unstressed interconnects were carefully examined with SEM and TEM techniques, especially with regard to void densities, void sizes and characteristic lengths between void and hillock. The fatal void shape was related to current density and line width indicating that the failure mechanism changes with decreasing line width and decreasing current density.
Comparison of Film Quality and Step Coverage for Silicon Dioxide Dielectrics Formed by RTCVD Using Tetraethoxysilane and Silane
Authors: Miles D. S. , Harris G. S. , Venables D. , Mirabedini M. R. , Wortman J. J. , Maher D. M. , Hauser J. R. 
Published: April 2011

ABSTRACTRapid thermal chemical vapor deposition (RTCVD) oxides formed using TEOS and oxygen (O2) are compared with RTCVD oxides formed using silane (SiH4) and nitrous oxide (N2O). These oxides were deposited under varying pressure and gas composition to investigate the film step coverage and electrical properties. Cross-sectional scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used in determining the oxide step coverage. Excellent oxide conformality, greater than 90 %, was achieved with SiH4 and N2O over a wide range of aspect ratios. The average breakdown field obtained for the SiH4/N2O oxides is approximately 13 MV/cm, which is greater than values measured for oxides formed by conventional dry thermal process. Oxides deposited using TEOS typically have an average breakdown field of about 8 MV/cm. We conclude that the SiH4/N2O oxide process for the deposition of SiO2 films in a RTCVD reactor is a very promising candidate for sidewall spacer formation in advanced device applications.
I/F Noise Measurements in Al-Si, Al-Si-V and Al-Si-V-Pd Alloy Films
Authors: Kraayeveld J.R. , Augur R.A. , Dirks A.G. , Verbruggen A.H. , Radelaar S. 
Published: April 2011

ABSTRACTThe electromigration lifetime of Al-Si (1 at.% Si) can be greatly increased by alloying with V and Pd (0.1 at.% V, 0.1 at.% Pd). This study reports on l/fα (α≈l) noise measurements in Al-Si, Al-Si-V and Al-Si-V-Pd alloy films. Samples were prepared by direct current (DC) sputtering, e-beam lithography and reactive-ion etching. The samples were annealed at 450 °C for 30 min and were not passivated. Test line dimensions were 800μm×l.2μm×0.5μm. 1/f noise was measured by a high-resolution alternating current (AC) bridge technique, which ensured that no electromigration occurred during the measurements. The sample-to-sample variation in normalized 1/f noise intensity for Al-Si, Al-Si-V and, Al-Si-V-Pd, measured at room temperature, was less than 10%. The smallest noise intensities were observed in the Al-Si-V-Pd films. The temperature dependence of the 1/f noise of Al-Si films shows a maximum at 338 K allowing the determination of the activation energy of the noise generating process (Ea = 0.75 eV). Above 400 K the resistance of the samples became unstable preventing reliable noise measurements. The instabilities were probably caused by the dissolution of very small Si precipitates (<10 nm). This is important information because the dissolution will also take place during electromigration lifetime experiments.
Experimental Stress Analysis Methods and Some Thin Film Applications
Authors: Vrtis Joan K. , Farris Richard J. 
Published: April 2011

ABSTRACTInterference holographic methods are applied to thin film structures to determine their state of stress and their thermal and mass diffusion coefficients. Special sample preparation techniques are used to produce tensioned membrane samples that preserve the state of stress in coated parts. Then utilizing real time vibrational holographic interferometry methods, the total state of stress can be determined, two normal stresses and a shearstress. Similar samples exposed to moisture have their stress state altered by swelling and this can be monitored on a real-time basis and the influence on stress state and thethrough-the-thickness moisture diffusion coefficient can be determined. In related experiments using similar methods, the through-the-thickness thermal diffusion coefficient can be determined using pulse heating methods. These methods coupled with routine test methods enables one to fully characterize all of the orthotropic elasticity coefficients and transport characteristics needed for numerial analyses of thin film structures.
Effect of Power on the Properties of SiO2 Films Produced by Plasma-Enhanced Chemical Vapour Deposition
Authors: Tao Y. , Landheer D. , Baribeau J.-M. , Hulse J. E. , Xu D.-X. , Graham M. J. 
Published: April 2011

ABSTRACTThe effect of power on the properties of SiO2 films produced by direct plasma-enhanced chemical vapor deposition using nitrous oxide and silane with high helium dilution has been investigated. As the power increases the p-etch rate decreases while the frequency of the Si-O-Si stretching vibration measured by Fourier transform infra-red spectroscopy increases. However the refractive index of the films measured by ellipsometry is almost constant as is the electron density measured by low-angle x-ray reflection, indicating that the structural changes of the film with power do not relate to bulk density changes. The x-ray and ellipsometry measurements indicate the existence of a transitional layer with monolayer dimensions at the Si/SiO2 interface.
Characterization of PECVD SixOyNz:H Films and its Correlation to Device Performance and Reliability
Authors: Moinpour Mansour , Mack Ken , Cham Johnny , Moghadam Farhad , Williams Byron 
Published: April 2011

ABSTRACTFor integrated circuits, the integrity and film quality of the final passivation layer plays an important role in the device performance and reliability. Hydrogenated amorphous silicon oxynitride (α-SixNyOz:H) films deposited by plasma enhanced chemical vapor deposition (PECVD) have been extensively used for final device passivation applications. In this paper, a detailed characterization of PECVD oxynitride process for 200 mm Si wafer processing is presented. Silicon oxynitride of various compositions were deposited by changing the amounts of silane, ammonia, nitrogen and nitrous oxide in the reactant gas stream. Ultraviolet/Visible (UV/VIS) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, Rutherford backscattering spectrometry (RBS), and refractive index measurements were used to examine the variation in physical, optical and electrical properties. A correlation is observed between the oxynitride film composition, mainly N-H/Si-H ratio, and UV transmissivity (UV %T) which is of particular interest for memory applications. Effects of oxynitride film quality on e-test parameters and device performance are discussed.