bluuebunny/crossref_metadata_2025 huggingface dataset:
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

A 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

Direct 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

Photon 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

Amorphous 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

In 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

Electromigration 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

The 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

Electromigration 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

Because 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

Rapid 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

The 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

Interference 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

The 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

For 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.
Fabrication of Biaxially Oriented YBCO on (00l) Biaxially Oriented Yttria-Stabilized-Zirconia on Polycrystalline Substrates
Authors: Arendt Paul , Foltyn Steve , Wu Xin Di , Townsend John , Adams Chris , Hawley Marilyn , Tiwari Prabhat , Maley Martin , Willis Jeffrey , Moseley David , Coulter Yates
Published: April 2011

Ion-assisted, ion-beam sputter deposition is used to obtain (00l) biaxially oriented films of cubic yttria-stabilized-zirconia (YSZ) on polycrystalline metal substrates. Yttrium-barium-copper-oxide (YBCO) is then heteroepitaxially-pulse-laser deposited onto the YSZ. Phi scans of the films show the full-width-half maxima of the YSZ (202) and the YBCO (103) reflections to be 14° and 10° respectively. Our best dc transport critical current density measurement for the YBCO is 800,000 A/cm2 at 75K and 0T. At 75K, the total dc transport current in a 1 cm wide YBCO film is 23 A.
Substrate Effects on the Structure and Optical Properties of Epitaxial PbTiO3 Thin Films Prepared by Metal-Organic Chemical Vapor Deposition
Authors: Foster C. M. , Li Z. , Bai G. R. , You H. , Guo D. , Chang H. L. M.
Published: April 2011

Epitaxial PbTiOM3 films were prepared by metal-organic chemical vapor deposition (MOCVD) on MgO(001), SrTiO3 (001) and LaAlO3 (001) surfaces. Four-circle X-ray diffraction and optical waveguiding experiments were performed to characterize the deposited films. The films on all three substrates were single-crystal; however, the domain structure of the films was strongly dependent on the substrate material. Films on MgO and LaAlO3 substrates showed a large amount of 90° domain structures, whereas, the degree of twinning was greatly suppressed for films on SrTiO3. The refractive indices and optical birefringence of the films were measured as a function of wavelength using the film-prism coupling method. We found that for films on LaAlO3 (001), the ordinary index and for films on MgO(001) both the ordinary and extraordinary refractive indices were higher than those of bulk single-crystal PbTiO3. For films grown on SrTiO3 (001), the ordinary refractive index was very close to that of single crystal PbTiO3. We correlate the increased refractive index and the reduced birefringence to the degree of epitaxial strain and twinning in the samples, respectively.
PbTiO3 and PbZrxTi1-zO3 Films:Microstructure and Properties
Authors: Veirman A. E. M. De , Cillessen J. F. M. , Keijser M. De , Wolf R. M. , Taylor D. J. , Staals A. A. , Dormans G. J. M.
Published: April 2011

Hetero-epitaxial PbTiO3 films have been grown on different oxidic substrates. The orientation (the c or a axis being perpendicular to the substrate surface) and the morphology of the PbTiO3 film have been studied with transmission electron microscopy and X-ray diffraction. For non-volatile memory applications ferroelectric capacitors consisting of PbZrxTi1-xO3 films and Pt electrodes are most commonly used. The microstructure of PbZrxTi1-xO3 films (x=0.36 and x=0.71) grown on oxidized silicon provided with a Ti/Pt electrode, will be discussed in relation to the ferrroelectric properties. Finally, the use of La0.5Sr0.5CoO3 as an oxidic electrode is considered.
In Situ, Real-Time Analysis of the Growth of Ferroelectric and Conductive Oxide Heterostructures by a New Time-of-Flight Pulsed Ion Beam Surface Analysis Technique
Authors: Auciello Orlando , Krauss A. R. , Lin Y. , Chang R. P. H. , Gruen D. M.
Published: April 2011

A new time-of-flight ion scattering and recoil spectroscopy (TOF-ISARS) technique has been developed and is now used to perform in situ, real-time analysis of ferroelectric and conductive oxide layers during growth. Initial results presented here show various major effects, namely: (a) RuO2 films on MgO substrates appear to be terminated in O atoms on the top layer located in between Ru atoms lying in the layer underneath (This effect may have major implications for the explanation of the elimination of polarization fatigue demonstrated for RuO2/PZT/RuO2 heterostructure capacitors); (b) deposition of a Ru monolayer on top of a Pb monolayer results in surface segregation of Pb until a complete Pb layer develops over the Ru monolayer; and (c) a Pb/Zr/Ti layered structure yields a top Pb layer with first evidence of the existence of Pb vacancies, which also may have major implications in relation to the electrical characteristics of PZT-based capacitors.
Characterization of Sputtered Barium Ferrite Thin Films on Silicon Nitride Coated Carbon Substrates
Authors: Li Jinshan , Sinclair Robert , Rosenblum Stephen S. , Hayashi Hidetaka
Published: April 2011

Using facing target sputtering, randomly oriented crystalline barium ferrite(BaFe12O19, BaM) has been deposited onto a Ultra Densified Amorphous Carbon® (UDAC) substrate, producing high quality films in-situ at a substrate temperature of 6400°C without any post-deposition annealing. Cross section transmission electron microscopy (TEM) reveals that the films have columnar structure. A ˜100Å thick interdiffusion layer between BaM and silicon nitride underlayer was observed. Films grown at low oxygen partial pressure have lower saturation magnetization (Ms), that may be caused by the formation of some amorphous phase at the grain boundaries as noticed by plan-view TEM. The existence of the Fe2O3 phase in the BaM was also revealed by electron diffraction.
Epitaxial Magnetic Garnet Thin Films and Heterostructures by Pulsed Laser Deposition
Authors: Simion B. M. , Ramesh R. , Keramidas V. G. , Pfeffer R. L. , Thomas G. , Marinero E.
Published: April 2011

Epitaxial yttrium-iron-garnet (YIG) films, bismuth-iron-garnet (BIG) films, and YIG/BIG heterostructures have been grown on [111] oriented single crystalline gadolinium-gallium-garnet (GGG) substrates by pulsed laser deposition (PLD), using a KrF excimer laser system. The films under study were grown over a range of temperatures from 600°C to 800°C and at 100 mTorr oxygen partial pressure. The effects of oxygen partial pressure during cooling on the structure, composition and magnetic properties of the films were investigated, employing X-ray diffraction, Rutherford back scattering spectroscopy coupled with He ion channeling, and vibration sample magnetometry. All specimens under study indicated that, independent of the film-substrate mismatch, the grown films were single crystalline in the [111] orientation. Preliminary studies on the effects of cooling oxygen partial pressure on the film structure indicate an increase in lattice distortion in the direction normal to the film surface with decreasing pressure. The magnetic properties of the films are comparable to the YIG bulk properties, and all films indicated in plane preferential magnetization, independent of cooling conditions.
Study of Arsenic Evolution During RTA of Au-Based Ohmic Contacts to GaAs
Authors: Piotrowska A. , Kaminska E. , Guziewicz M. , Piotrowski T. , Kwiatkowski S.
Published: April 2011

We report on the formation of AuZn/p-GaAs ohmic contacts by short time annealing either in open or closed configuration with a dielectric or metallic capping layer. Quantitative determination of the amount of arsenic losses was of primary concern. This was studied using the Cr-collector method, applying three types of collectors all of them using 100 nm thick Cr film for seizing evaporative As losses. In the first type, the Cr film was deposited onto oxidized Si substrate. In the second type - quartz substrate was used for the deposition of chromium film while the third collector used natural mica as a substrate for the Cr film. The obtained results show that the loss of arsenic is reduced below 2×1014 atom/cm2 using thin 20 nm Au/10 nm Zn/60 nm Au metallization annealed with a capping layer at 440°C for 15 sec. Electrical measurements indicate that under these conditions good ohmic contacts are obtained.
Dielectrics on Silicon Thermally Grown or Annealed in a Nitrogen Rich Environment
Authors: Harrison H. Barry , Misiura Andrew , Dimitrijev Sima , Sweatman Denis , Yao Z. , Yeow Y.T.
Published: April 2011

In this paper we review various methods of improving the properties of extremely thin dielectrics (<20 nm) using a nitrogen rich environment. The three main gases considered being ammonia, and nitrous and nitric oxides. We present original results for nitric oxide exposed silicon and suggest that for ultra thin dielectric (<5 nm) that these layers are generally superior to any others, whilst for thicker layers oxides annealed in nitrous oxides appear to display the best properties.
Electrical Properties of Stacked RTO/RTCVD Oxides as Gate Dielectrics
Authors: Misra V. , Xu X-L. , Wortman J.J.
Published: April 2011

To meet the stringent demands of high quality gate performance in advanced devices, a more robust gate dielectric is needed. A stacked structure consisting of thermal oxide and deposited oxide is a potential candidate since it offers certain advantages over single layer oxides such as 1) reduced defect density, 2) reduced stress at the SiO2/Si interface due to stress compensation between the thermal and the deposited oxide, 3) less silicon consumption and 4) reduced thermal budget. In this study, stacked oxides consisting of RTO and RTCVD oxides are characterized. In contrast to other studies which use conventional LPCVD methods to form the top oxide, these stacked oxides have the advantages of rapid thermal and in-situ processing, which produces excellent bulk and interfacial properties. Electrical characterization has shown that these stacked oxides have superior performance compared to single layer furnace or deposited oxides.
Borophosphosilicate Glass(BPSG) Fusion Using Rapid Thermal Annealing and Steam Reflow: Physical Properties and Device Implications
Authors: Maxim Mike , Moinpour Mansour , Chu John , Nguyen Hien , Freiberger Phil , Stenton Nicky
Published: April 2011

With decreasing device geometry to below sub micron dimensions, there is a greater emphasis on reducing the thermal budget by shortening and/or eliminating high temperature processing steps. The use of RTP for borophosphosilicate glass (BPSG) fusion/reflow process, which is conventionally performed in diffusion furnaces in temperature range of 850-900 °C, has gained some acceptance in recent years. BPSG films were prepared by an atmosphericpressure chemical vapor deposition(APCVD) process. BPSG film properties such as stress, shrinkage, dopant uniformity and surface stability, step coverage, and flow angle, have been examined as a function of densification/reflow cycle. We used RTP-only, furnace-only, and RTP/furnace reflow annealing cycles. The impact of various BPSG fusion scenarios on underlying Ti salicide and P-channel and N-channel devices is discussed.
Advanced Dram Cell Dielectric Films using Rapid Thermal Processing
Authors: Thakur Randhir P.S. , Mathews Viju K. , Fazan Pierre C.
Published: April 2011

The reliable operation of a dynamic random access memory (DRAM) device requires a minimum level of charge to be stored in the capacitor. The nonlinear dependence between the scaling of the minimum charge and the cell area for higher DRAM densities is the driving force in the development of exotic capacitor structures and advanced cell dielectric materials. The conventional option of reducing the thickness of the silicon nitride dielectric films for high density DRAM applications will eventually be constrained by the increase in the leakage current due to direct carrier tunneling or by the decrease in the oxidation resistance of the films.

In this paper we discuss the use of rapid thermal processing to modify the interface between the polysilicon storage node of the capacitor and the silicon nitride to improve the electrical and structural characteristics without any loss in capacitance. The influence of electrode roughness on the electrical behavior will also be discussed for the various dielectric stack combinations.
Steady-State Versus Rapid Thermal Annealing of Phosphorusimplanted Pseudomorphic Si(100)/Ge0.12Si0.88
Authors: Lie D. Y. C. , Song J. H. , Theodore N. D. , Eisen F. , Nicolet M.-A. , Cams T. K. , Wang K. L. , Kinoshita H. , Huang Tzu-Hsin , Kwong D. L.
Published: April 2011

Pseudomorphic Ge0.12Si0.88 films 265 nm thick grown by molecular beam epitaxy on p- Si(100) substrates were implanted with 100 keV 31P at room temperature for a dose of 5 x 1013/cm2. The projected range of the implanted P is about half the epilayer thickness. The implanted layers, together with non-implanted virgin samples, were subsequently annealed by both rapid thermal annealing in nitrogen and by steady-state furnace annealing in vacuum. The damage and strain of the annealed layers were studied by 4He channeling and x-ray doublecrystal diffraction. For a dose of 5 x 1013 P /cm2, both the damage and strain introduced by implantation can be completely removed, within instrumental sensitivity, by rapid thermal annealing at 700 °C for 10 - 40 s. Furnace annealing at 550 °C for 30 min for this sample removes most of the damage and strain induced by implantation. Furnace annealing at 700 °C or higher worsens the crystallinity of the layer and the strain relaxes. Hall measurements were performed on the same samples. Furnace annealing cannot achieve good dopant activation without introducing significant strain relaxation to the heterostructure, while rapid thermal annealing can.
Removal of Microcontaminants From Surfaces Using a Chemicalfree, Laser-Assisted Process
Authors: Engelsberg Audrey C.
Published: April 2011

The ability to control and eliminate microcontamination from the manufacturing process is becoming a critical technology issues for such diverse industries as semiconductors, aerospace, and automotive. Current industrial cleaning practices use large amounts of water and chemicals which require disposal. Dry environmentally benign technologies can be alternatives. In this paper, we will look at an alternative technology which consists of deep ultraviolet photons coupled with a flowing inert gas, and compare it to current wet cleaning practices in the semiconductor industry.
A Chemical Heat Pump With An Endothermic And Reversible Chemical System Incorporated
Authors: Tsuji M. , Wada Y. , Kodama T. , Hasegawa N. , Tamaura Y.
Published: April 2011

A conceptual design of chemical heat pump system with reactive ceramics incorporated has been proposed and exemplified by several chemical reactions on activated metal oxides. It functions at temperatures of waste heat. The system involves the following endothermic reactions; (1) activation of metal oxide ceramics to activated ceramics using an oxygen-free inert gas, (2) H2O decomposition by the activated ceramics to form H2 gas at 300°C, (3) formation of CH4 from H2 and CO2 at 200–300°C, (4) CO2 decomposition to gaseous CO on activated oxide ceramics at 600–700°C. The working materials are typically magnetite, metal-bearing ferrites, transition metal-modified magnetite and other metal oxides. These basic reactions have been demonstrated to occur at temperatures of waste heat. The chemical heat pump will be effectively operated by incorporating their oxide membrane into the system. These findings have facilitated us to exploit a new field of research work. The above integrated chemical system may help the mitigation of CO2 in the global scale.
A New Preparation Technique of Activated Carbon Fiber
Authors: Ruowen F U , Lu Yun , Lu Haifeng , Zeng Hanmin
Published: April 2011

In this paper, the characteristic of a new preparation technique of activated carbon fiber (ACF) was discussed. The structures and properties of the ACF produced were investigated simultaneously. The experimental results indicated that this new technique is a high efficient method for the preparation of ACF. It needs simple facilities and is easy to be operated. The products obtained possess high specific surface area and adsorption capacity.
Studies on the Structure and Reduction Property of Metal-Containing Activated Carbon Fiber
Authors: Fu Ruowen , Lu Yun , Yue Zhongren , Zeng Hanmin
Published: April 2011

In order to improve the reduction ability and capacity of ACF, some metal-containing ACF (Me-ACF) were prepared. Their structures and reduction properties were investigated at the same time. On the basis of experimental results, a redox mechanism was proposed.
Heterogeneous Nucleation of Calcium Oxalate on Native Oxide
Surfaces
Authors: Song Lin , Pattillo Michael J. , Graff Gordon L. , Campbell Allison A. , Bunker Bruce C.
Published: April 2011

The aqueous deposition of calcium oxalate onto colloidal oxides has been
studied as a model system for understanding heterogeneous nucleation
processes of importance in biomimetic synthesis of ceramic thin films.
Calcium oxalate nucleation has been monitored by measuring induction times
for nucleation using Constant Composition techniques and by measuring
nucleation densities on extended oxide surfaces using an atomic force
microscope. Results show that the dependence of calcium oxalate nucleation
on solution supersaturation fits the functional form predicted by classical
nucleation theories. Anionic surfaces appear to promote nucleation better
than cationic surfaces, lowering the effective energy barrier to
heterogeneous nucleation.
Volatile Mixed Metal Y-Ba and Ba-Cu Precursors for Mocvd of High
Tc Superconductors: A Way to Improve the Transport of Barium
?
Authors: Hubert-Pfalzgraf Liliane G. , Labrize Florence , Guillon Herve , Tobaly Patrick
Published: April 2011

The fluoroisopropoxide ligand (HFIP) has allowed the synthesis of
mixed-metal homoleptic Ba2Y and CuBa alkoxides. However, although
these species are all volatile, their poor thermal stability precludes their
use as CVD precursors. Their properties have thus been optimized by
introduction of 2,2,6,6-tetramethylheptane-3,5-dione (thdH) in the metal
coordination sphere. Compounds such as
Y2Ba(μ-HFIP)4(thd)4, the first volatile
Y-Ba species reported so far, as well as
BaCu2(HFIP)4(thd)2 and
YCu(HFIP)2(thd)3 have been obtained. These
heterometallic ϐdiketonatoalkoxides have been characterized by a variety of
techniques including X-ray diffraction, mass spectrometry, vapor pressure
measurements and thermogravimetric analysis. Preliminary data on thermal
decomposition experiments are given.
Leaching Behavior of Edta In A Silica Sol-Gel
Matrix
Authors: Oka Kris S. , Mackenzie J.D.
Published: April 2011

Ethylene diamine tetra-acetic acid (EDTA) doped silica gels were made by the
sol-gel process for the potential application as a filter for heavy metal
ions in wastewater. The behavior of the organic molecule in the matrix was
studied by investigating the percentage of EDTA leached out with a variation
in the timing of addition of the EDTA molecule into the starting silica gel
solution. Leach tests using water as the medium were performed for 2, 12 and
24 hours in order to determine the amount of EDTA trapped in the pores or in
the matrix. A minimum amount of EDTA leached from the gels was detected in
the samples to which EDTA was added 4 hours after initial hydrolysis of
TEOS. This result was correlated to having a greater percentage of pore
volume in the range of 15–20 Å, which was further substantiated with density
measurements. The physical changes in the silica matrix altering the pore
volume distribution were attributed to the addition of the water into which
the EDTA molecule was initially dissolved.
Tailoring Suspension Flow for the Gelcasting of Oxide and
Nonoxide Ceramics
Authors: Omatete O. O. , Bleffir A.
Published: April 2011

The rheology of gelcasting slurries of concentrated (30 - 60 vol%) alumina,
zirconia, silicon nitride, and sialon powders with isoelectric points
varying between pH 5 and 9, was studied by measuring the viscosity and yield
stress as functions of pH. Typically, the rheology is non-Newtonian. The
lowest values of viscosity and yield stress that permit the highest solids
loading were obtained at high and low pH values, where the powders are
colloidally stable, far from the isoelectric points. This relationship
applies whether or not a polymer dispersant is present. The acrylamide
monomer which is used in gelcasting slurries, lowers these non-Newtonian
properties permitting the preparation of more concentrated slurries. Fluid
and pourable gelcasting slurries of each powder had apparent viscosities and
yield stresses less than 2.0 Pa·s and 50 Pa, respectively.
Surface Chemical Structure of Sío2-TiO2 Sol-Gel
Powders
Authors: Ingo G.M. , Padeletti G. , Dire' S. , Babonneau F.
Published: April 2011

Amorphous SiO2, TiO2 and x SiO2-(1-x)
TiO2 powders, with nominal values of x=0.9, 0.7 and 0.5, have
been prepared via sol-gel, using silicon tetrahoxysilane (TEOS) and titanium
tetraisopropoxide Ti(OPri)4. X-ray photoelectron
spectroscopy (XPS) and X-ray induced Auger electron spectroscopy (XAES) are
used for studying the surface chemical structure of the powders as a
function of the air thermal treatment temperature up to 1273 K. For the
whole range of temperature, XPS and XAES signals indicate that silicon and
titanium are present as Si4+ and Ti4+ oxides. From the
line shape of the O 1s peak, it is possible to distinguish between the
single O-Ti and O-Si bonds and to disclose also the presence of Si-O-Ti
cross linking bonds that are supposed to act as bridges between
SiO2 and TiO2 moieties. Starting from 873 K, the
Si-O-Ti bonds are broken and formation of a low amount of new Ti-O and a
higher amount of Si-O bonds takes place. Si/Ti atomic ratios obtained by
curve fitting the O Is peaks and from Ti 2p3/2 and Si 2p peaks,
confirm the silicon oxide surface enrichment. Furthermore, with increasing
temperature, XAES data indicate the formation of crystalline phases.
A General Nonhydrolytic Sol‐Gel Route to Oxides
Authors: Acosta Sylvie , Arnal Pascal , Corriu Robert J.P. , Leclercq Dominique , Mutin P. Hubert , Vioux Andre
Published: April 2011

A nonhydrolytic sol‐gel route based on the condensation between chlorides
and oxygen donors such as ethers and alkoxides is presented. Four examples,
silica, alumina, titania and binary oxides in the Al/Si system show that
this is a general route. The mechanism of this condensation is completely
different from the one of classical sol‐gel process, since it implies
nucleophilic substitution at the carbon center instead of the metal center.
As a consequence, the differences in reactivity between different metals are
reduced. In addition, the structure of the precursors may be retained in the
gel. Thus, the nonhydrolytic sol‐gel process is very efficient for the
preparation of homogeneous bicomponent oxides. Futhermore, nonhydrated gels
are formed, which allowed us to prepare amorphous aluminas with high surface
areas.
Sol-Gel Preparation and Characterization of Niobia thin Films
for Catalytic Sensor Applications
Authors: Ochoa Rosibel , Miranda Raul
Published: April 2011

Thin films of niobium pentoxide were deposited on quartz plates by
spin-coating a solution of niobium ethoxide in ethanol. The films were
tested as potential selective gas sensors by exposing them to various
reducing environments. It was found that they were selective and sensitive
to ammonia. This sensitivity was attributed to the formation of
donor-acceptor complexes between chemisorbed ammonia and Lewis acid sites on
the solid.
Contact Angle Measurement and Its Application To Sol-Gel
Processing
Authors: Stein D. J. , Maskara A. , Hæreid S. , Anderson J. , Smith D. M.
Published: April 2011

Capillary stresses during drying that result from the contact angle of a
liquid solvent to a gel, surface tension, and pore size have an immense
effect on the dried gel. The extent to which the gel shrinks is a balance
between the capillary stress and the solid matrix strength. The dynamic
contact angles and surface tensions of various solvents commonly employed in
sol-gel processing on silica gels of various surface chemistries have been
evaluated. A thin, dense coating of silica gel was formed by dip coating a
standard glass slide in an acid catalyzed silica sol and drying. Some of the
sample surfaces were organically modified. Dynamic contact angles were
determined using a modified Wilhelmy plate technique. Solvent surface
tensions were determined using the De Nouy ring technique. The bulk modulus
of wet gels were determined with a three point bend experiment. We have
found that contrary to previous investigators, who attributed different bulk
densities obtained after drying from various alcohols to contact angles
variations, gel shrinkage during drying is actually due to slightly
different surface tensions and degrees of depolymerization of the gel
network.
Grain Boundary Phase Analysis of Silicon Nitride by a Newly
Developed 300kv Field-Emission Electron Microscope
Authors: Bando Y. , Suematsu H. , Mitomo M.
Published: April 2011

The grain boundary phase of silicon nitride containing additives
Y2O3 and Nd2O3 has been
studied by means of a newly developed 300kV field emission ATEM. The
composition of the two-grain boundary phase of about 1 nm thick is
successfully determined. It is then found that the compositions among the
grain boundaries are not the same and the additives of
Y2O3-Nd2O3 are poor in the
two-grain boundary, while they are rich in the triple points.
Liquid Crystal Templating Effects on Silica Gels Synthesized
using Quaternary Ammonium Surfactants
Authors: Dabadie T. , Ayral A. , Guizard C. , Cot L. , Robert J.C. , Poncelet O.
Published: April 2011

The use of lyotropic liquid crystal phases is a promising tool in tailoring
the porous structure of inorganic gels. In this work, we examine the effect
of hexagonal liquid crystal phases produced with quaternary ammonium
surfactants on the textural ordering of silica gels.

The sol-gel polymerization of the silicon alkoxide precursor
(tetramethoxysilane) is followed by 29Si NMR and rheological
measurements. The structural evolution of the material from the starting sol
to the thermally treated gel is studied using low angle X-ray diffraction.
The textural characteristics of the gels are correlated with the nature of
the surfactant molecules.
Stratification of Fullerenes
Authors: Levon K. , Weng D. , Mao J. , Lee H.K.
Published: April 2011

Dodecylated C60 {(Do)nC60(H)n} and butylated C60 {(Bu)nC60(H)n} were synthesized. Spectroscopic and thermal methods, mass spectrometry, XPD, have been employed to characterize the products. X-ray Powder Diffraction (XPD) results reveal that the facecentered- cubic (fcc) structure of C60 expands to a primitive hexagonal structure upon butylation and to a layered structure upon dodecylation. Butylated C60 diffraction pattern has been indexed as a primitive hexagonal structure with ao = 11.5 angstroms and axial ratio = 1.169. The dodecylated C60 also shows sidechain melting behavior with a transition temperature of around 25°C. The paraffinic crystals are produced by the interdigitation of the sidechains. Butylated C60 does not show any sidechain melting.
Catalytic Growth of Carbon Nanofibers and Nanotubes
Authors: Terry R. , Baker K. , Rodriguez Nelly M.
Published: April 2011

Carbon nanofibers and nanotubes have been prepared from the decomposition of carbon containing gases with the aid of an iron catalyst particle. The physical characteristics as well as the degree of crystalline perfection of the structures were found to be dependent on the nature of the metal particle and the conditions at which the material was grown. Transmission electron microscopy revealed that nanofibers were obtained from large catalyst particles (>20 nm), whereas nanotubes were formed by the aid of smaller particles (<20 nm). The orientation of the graphitc platelets in the carbon nanofibers was dependent on the alignment of the planes at the rear faces of the iron particle that were responsible for the precipitation of carbon. Carbon nanofibers exhibited reactivity in carbon dioxide comparable to that of single crystal graphite under the same conditions.
Synthesis of Single Walled Buckytubes
Authors: Yadav Tapesh , Withers James C. , Seraphin Supapan , Wang Su , Zhou Dan
Published: April 2011

We report here a study of alternative methods for producing single walled buckytubes. In this study, we prepared graphite electrodes packed with different metal or metal combinations. These electrodes were arced under similar conditions and the products so formed characterized with TEM. The results demonstrate that single walled tubes can be synthesized in many ways and at high yields. The results also suggest that the use of more than a single dopant may provide significant advantages in the commercial synthesis of buckytubes.
High Rate, High Quality, Diamond Synthesis by the Combustion Flame Process
Authors: Ravi K.V. , Olson D.S. , Koch C.A.
Published: April 2011

Among the various low pressure techniques being developed for the synthesis of diamond films and bulk diamond slabs the combustion flame synthesis process has some distinct advantages. In this approach the combustion reaction between acetylene and oxygen is utilized to generate the requisite energy to activate excess acetylene in the gas mix leading to the deposition of diamond films on a temperature controlled substrate brought into contact with the flame. Other diamond synthesis approaches, such as microwave enhanced and the filament assisted chemical vapor deposition processes, and the various arc jet techniques utilize mixtures of hydrogen and methane as the process gases. Oxygen and oxidizing specie ( such as OH radicals) in the flame ambient may be much more effective than atomic hydrogen in promoting the growth of diamond over the growth of graphite and other non- diamond forms of carbon. In addition this technique enables the growth of diamond at high rates and is relatively easily scaled for large area synthesis. In this paper a discussion of this technique is presented drawing upon recent research by the authors as well as published work to present a general discussion of the issues involved in the development of this technique of low pressure diamond synthesis.
Pulsed-Laser Deposition and Characterization of Amorphous Diamondlike Carbon Films
Authors: Huai Y. , Broughton J. N. , Gat E. , Chaker M. , Borges C. F. M. , Beaudoin Y. , PÉpin H. , Moisan M.
Published: April 2011

Unhydrogenated amorphous carbon films were deposited by KrF pulsed laser ablation of graphite under a laser power density of 8×108 W/cm2. The films were characterized using x-ray reflectivity, optical transmittance, spectroscopic ellipsometry and Raman spectroscopy. The physical, optical and bonding properties of the films have been investigated in detail as functions of substrate temperatures Ts (22-300°C) and post-annealing temperatures. Films deposited at Ts, <200°C possessed diamond-like properties with mass densities p=2.8-3.1 g/cm3 and optical bandgaps Eg,=1.5-2.2 eV. Above Ts,=200°C, the films showed typical graphite characteristics. The diamond-like films annealed at temperatures up to 750°C show excellent thermal stability.
Evaluation of Graphitic Foams as Low Mass Structural Materials
Authors: Hall Richard B. , Hager Joseph W.
Published: April 2011

Graphitic foams offer exciting potential for mass savings in structures. A hypothetical family of graphitic foams having ligament mechanical properties identical to those of P120 graphite fiber is considered; the mechanical properties of the hypothetical foams are viewed as realistic upper bounds on the performance of this class of materials. Various commercially available materials are compared to the hypothetical foams for application to tension bars, beams in bending and buckling, and plates in bending and buckling.
DC-Magnetron Sputtered Silicon Carbide
Authors: Tenhover M. , Ruppel I. B.
Published: April 2011

The preparation and properties of relatively thick films of DC magnetron sputtered SiC films is described. The films were prepared using a new ceramic sputter target material. The new target material is called Hexoloy® SG–90. It is an electrically conductive, dense ceramic material which can be used as a sputter target to yield insulating amorphous SiC thin films on room temperature substrates.
Elastic Constant Effect on the Critical Thickness of an Epilayer
Authors: Zhang Tong-Yi
Published: April 2011

The effect of elastic constants on the critical thickness of an epilayer is investigated. The results indicate that the self energy of the dislocation is controlled by the soft phase between the epilayer and the substrate, while the interaction energy only depends on the elastic constants of the epilayer. It is easier for a dislocation to be formed if the substrate is softer than the epilayer, and consequently the critical thickness is smaller. On the other hand, a soft epilayer can have a large thickness without any mismatch dislocation.