bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Grinding/Polishing Tool for TEM Sample Preparation
Authors: Klepeis S. J. , Benedict J. P. , Anderson R. M. 
Published: March 2011

ABSTRACTA grinding/polishing tool has been developed for preparing TEM samples. The hand-held tool is 2.50″ in diameter and 3.0″ high. Rough-cut samples, 300 to 600 microns thick, are routinely polished to 5 microns thick in four to six hours using this tool. As these 5 micron samples are so thin and uniform, a separate dimpling operation can be eliminated. Likewise, the time required to ion-mill the sample can be reduced to 0.5 to 2.0 hours – greatly reducing ion-milling artifacts and significantly increasing the area viewable by TEM. The process is equally effective for all classes of samples: Silicon devices, ceramics or metals – in either cross-section or planar views.
Preparation of Multilayer Optical Coatings for Tem Cross-Sectional Microanalysis by Ultramicrotomy
Authors: Swab P. , Klinger R. E. 
Published: March 2011

ABSTRACTUltramicrotomy is a technique for cutting cross-sections of material which was originally used by biologists for soft tissue analysis. With only a few changes to accommodate the hard dielectric coatings and substrates, the technique may be used to prepare specimens of optical multilayer devices for cross-sectional transmission electron microscopy (XTEM).The ultramicrotome, mounted on a vibration damped table, is capable of cutting uniform 40 nm thick cross-sections of materials with a diamond knife. An epoxy embedded sample is cycled past the knife at a controlled rate and advanced by a precise, preset distance on each pass. As each section is cut, it comes off the knife edge to a reservoir of water where, while floating, it can be picked up on a TEM grid.Artifacts generated by this mechanical technique for preparing thin cross-sections are readily apparent yet easy to disregard. TEM analysis of these cross-sections provides direct imaging of real samples for accurate feature and thickness measurement and direct chemical and crystalline structure analysis.
Xtem of Silicon Vlsic Device Structures
Authors: Knoell Robert V. 
Published: March 2011

ABSTRACTThe use of XTEM (cross-sectional TEM) as a diagnostic tool for quality control of device processing has experienced a surge of popularity recently due to the need for better feature resolution and the improvement in equipment and techniques for preparing such samples. As device features shrink below one micrometer, interface morphology and the detection of microstructural defects make TEM a most effective imaging tool. The demand for XTEM is tempered by problems in sample preparation, which impose restraints on turnaround time and image quality, especially for devices utilizing multilevel metallizations. A reliable technique for preparing these devices for XTEM observations, along with helpful hints to integrate into a sample preparation routine, will be presented. This technique reduces turnaround time to about a day and a half per group of samples. The rate of success is high if care is exercised, and all parts of the sample, metallized or not, are electron transparent to produce a clear image with minimized brightness contrast between layers. Finally, micrographs will be presented to illustrate what can be achieved with this technique and what features of interest can be observed for failure analysis determination.
Specimen Preparation for Transmission Electron Microscopy of Metals
Authors: Goodhew Peter J. 
Published: March 2011

ABSTRACTThe aim of thin foil preparation is to produce a specimen for microscopy which is representative of a larger volume of material, and in which the detail can be seen and interpreted. It is in general necessary to undertake some initial preparation before the final thinning process. Both stages are described. The final preparation methods described in this paper include electropolishing, ion beam thinning, ultramicrotomy and replication. A guide to the choice of technique is presented.
Cross-Sectional TEM Sample Preparation for Multilayer Electronic Materials
Authors: Chang Peng-Heng , Coviello M. D. , Scott A. F. 
Published: March 2011

ABSTRACTThe preparation of cross-sectional TEM samples from multilayer materials commonly encountered in electronic industry is difficult in general due to the large variation in chemical and physical etching rate. We have developed a technique consisting of a median incidence angle ion sputtering to perforation followed by a short time (<2 hours) low incidence angle sputtering with the glue line direction shielded from the ion beams. This technique takes advantage of the fast sputtering rate associated with the median incidence angle sputtering initially. The near normal (relative to the glue line direction) low angle sputtering in the second step smooths out any non-uniformity in thickness due to the strong dependence of sputtering rate on the sputtering angle. High quality TEM samples prepared from many different types of multilayer structures using this technique are demonstrated.
ArF Excimer Laser-Induced Epitaxial Growth of GaAs Films on Si
Authors: Chu Shirley S. , Cpu T. L. , Chang C. L. 
Published: March 2011

AbstractEpitaxial gallium arsenide films have been deposited on single crystalline GaAs substrates of {100} orientation and Si substrates of 3° off the {100} orientation by ArF excimer laser-induced metalorganic chemical vapor deposition. The important process parameters include the cleanliness of the substrate surface, substrate temperature, the composition, flow rate, and pressure of the reaction mixture, and the pulse energy and pulse rate of the laser. Particular attention was directed to the in-situ cleaning of the substrate surface prior to the deposition process. Homoepitaxial gallium arsenide films of good structural perfection have been deposited at 425°- 500 ° C and their single crystallinity has been confirmed by transmission electron microscopy. The carrier concentration decreases with increasing AsH3/(CH3)3 Ga molar ratio and with decreasing substrate temperature. Lower growth rate during the initial stage of deposition is necessary to obtain heteroepitaxial gallium arsenide films on Si with good structural perfection. The TEM examination of GaAs films of 0.15–0.2 µm thickness deposited on Si substrates at 500 °C has shown that stacking faults were present in the GaAs films; however, there is no apparent threading dislocations in the surface region of the thin GaAs film.
Monolithic GaAs/Si Integration
Authors: Turner George W. , Choi H. K. , Mattia J. P. , Chen C. L. , Eglash S. J. , Tsaur B-Y. 
Published: March 2011

AbstractThe recent demonstrations of room-temperature cw operation of diode lasers fabricated in GaAs/AlGaAs layers grown on Si wafers have encouraged efforts to develop monolithic GaAs/Si integration technology for applications such as optical interconnects between VLSI subsystems. This paper summarizes our current work in this area, which is focused on the development of a highspeed, MSI-scale monolithic GaAs/Si test chip that integrates Si MOSFET circuits with diode lasers, LEDs, photoconductive detectors, and MESFET logic circuits fabricated in GaAs/AlGaAs layers grown by molecular beam epitaxy. Growth issues and processing considerations that affect device and circuit performance are addressed, and the characteristics of LEDs monolithically integrated with Si driver circuits and of GaAs microwave MESFETs fabricated on high-resistivity Si substrates are reported.
Heterogeneous Strain Relaxation in GaAs on Si (100)
Authors: Freundlich A. , Neu G. , Leycuras A. , Carles R. , Verie C. 
Published: March 2011

AbstractResidual stress in MOVPE grown GaAs on (100)Si substrates is investigated using Haman spectroscopy, X-ray diffraction, low temperature photoluminescence and photoluminescence excitation spectroscopy experiments. At room temperature, 2 µm-thick GaAs/Si is found to be under biaxial (100) tensile stress of X = 1.8 ± 0.3 kbar, near the epilayer surface. The stress magnitude decreases as the distance from interface decreases. PL and PLE studies on post-growth thermally annealed GaAs/Si reveal coexistence of unstrained and strained GaAs.
CaP/Si Heteroepitaxial Layers with Reduced Defect Density
Authors: Blakeslee A.E. , Al—jassim M.M. , Olson J.M. , Jones K.M. , Vernon S.M. 
Published: March 2011

AbstractIt is shown that GaP layers grown upon Si at a single temperature of 900ºC can have a crystalline quality superior to that exhibited by previous two—step and one—step growth methods. The layers are characterized by a planar network of misfit dislocations confined to the interface plane an a reduced density of threading dislocations (low 106 cm-2; previously >108). Very few threading defects were observed in areas devoid of amorphous oxide contamination, as shown by HREM examination of cross—sectional samples. A low growth rate during nucleation enhances crystalline perfection, since it decreases the tendency toward three—dimensional islanding.
Initial Stages of GaAs Epitaxy on Si
Authors: Biegelsen O. K. , Ponce F. A. , Krusor B. S. , Tramontana J. C. , Yingling R. D. , Bringans R. D. , Fenner D. B. 
Published: March 2011

AbstractThe initial stages of heteroepitaxial growth of GaAs on Si have been observed using a technique of graded-thickness sample deposition. We find that an initial uniform passivating layer is grown, followed by three-dimensional nucleation determined by Ga diffusion and clustering, followed in turn by an interfacial reaction limited island growth mechanism. Results for various substrate temperatures and substrate orientations are consistent with the simple models of nucleation and growth.
An Investigation of the Heteroepitaxial Growth of Beta—silicon Carbide Thin Filmson Silicon Substrates
Authors: Glass J. T. , Wang Y. C. , Kong H. S. , Davis R. F. 
Published: March 2011

AbstractHigh purity β—SiC films have been epitaxially grown on Si (100) and off-axis Si (100) substrates. Conventional chemical vapor deposition at 1633K and 1 atm using SiH4 and C2H4 reactants in an H2 carrier gas was employed for this growth. Large differences in lattice parameter and thermal coefficients of expansion between the film and the substrate were partially compensated for by growing aninitial “conversion layer.” Plan view and cross—sectional transmission electron microscopy were utilized to study the conversion layer and the defects present in the films. A high density of stacking faults and dislocations were present in allthe films grown on Si, however, antiphase boundaries were eliminated when certain off—axis Si (100) substrates were employed. The effects of misorientation angle and substrate preannealing were investigated. The electrical properties of the β-SiC films were also studied using differential capacitance—voltage and Hall effect measurements as well as the I—V characteristics of Au—β—SiC Schottky diodes. It was found that the elimination of antiphase boundaries reduced leakage current but did not significantly effect carrier concentration or Hall electron mobility. Finally, the I—V characteristics of a Metal—Semiconductor—Field—Effect—Transistor (MESFET) have been evaluated for a β—SiC filmon an on—axis Si (100) substrate.
Schottky Diode Characteristics of CVD—Grown β —SiC Epitaxial Films on (n11) Silicon Substrates ( n= 1,3,4,5,6 ).
Authors: Fujii Yoshihisa , Ogura Atsuko , Furukawa Katsuki , Shigeta Mitsuhiro , Suzuki Akira , Nakajima Shigeo 
Published: March 2011

AbstractSchottky barrier contacts have been made on CVD—grown β - SiC on Si substrates, and their C—V and I—V characteristics are measured. Dependence of the Schottky characteristics on Si substrate orientation ((n11),(n=1,3,4,5,6), and (100)) is examined. The Schottky diodes of the β-SiC films on Si (611), Si(411), and Si (111) show excellent characteristics compared with the conventional Schottky diodes using Si(100) substrates. That is, reverse leakage currents are small, ideality factors are close to unity, and barrier heights are larger.
Improvement in Surface Morphology and Crystal Epitaxial CaF2 on Si (100) Through two Mbe Growth Stages
Authors: Morimoto Yoshihiro , Matsumoto Shoichiro , Sudo Shoji , Yoneda Kiyoshi 
Published: March 2011

AbstractWe report the first study on improvement in surface morphology and crystal quality of as—grown epitaxial CaF2 film on a (100) Si substrate grown through two MBE growth stages without any post-growth treatment. The degree of improvement in surfacemorphology and crystal quality depends not only on the thickness of an initial thin CaF2 film grown at the early growth stage of 550ºC but also on both the subsrate temperature and thickness of a sequential grown CaF2 film used for thesecond growth stage. Under optimum conditions, the CaF2 films exhibited high quality with an RBS/channeling minimum yield of 4%, together with a very smooth surface morphology without any other nuclel or cracks.
Epitaxial BaF2-CaF2 Stacks on Si(111) and Si(100)
Authors: Blunier S. , Zogg H. , Weibel H. 
Published: March 2011

AbstractStacks of non lattice matched epitaxial CaF2, SrF2 and BaF2 layers have been grown by MBE onto Si(lll), and, for the first time, onto Si(l00). On CaF2 covered Si(lll) surfaces, BaF2 grows in a 2—d way after formation of the first monolayers despite a lattice mismatch of 14%. On Si(l00), BaF2 grows with the same (100)—lattice orientation as the underlying substrateif at least a thin (=100 Å) intermediate CaF2 layer is deposited first. Growth is 3—d on (100)—surfaces because of the large (100)—surface free energy of the group IIa—fluorides. By applying in situ short anneal cyclesat the first stages of growth, the crystallographic quality increases for (111)— as well as for (100)—orientation.
Localized Epitaxial Growth of IrSi3, ReSi2, and Rh3Si4 on (111) and (00l)Si
Authors: Chu J.J. , Chen L.J. , Tu K.N. 
Published: March 2011

AbstractIrSi3, ReSi2, and Rh3Si4 have been grown epitaxially on (111) and (001) Si. Transmission electron microscopy has been applied to characterize the epitaxial films. The orientation relationships between epitaxial sulicides and substrate silicon were determined from electron diffraction analysis. The average size, areal fraction of surface coverage, and fraction of epitaxy were measured. The silicide/silicon interface structures were analyzed.The best epitaxy in the three metal/Si systems was found to be epitaxial IrSi3 in Ir/(111)Si samples annealed at 1000 °C. Epitaxial regions, as large as 40 μm in size, were observed. Three major modes of IrSi3 epitaxy on (111)Si were identified.
Technological Prospects for Germanium Silicide Epitaxy
Authors: Bean John C. 
Published: March 2011

AbstractThis paper describes preliminary device work on GexSil−x based devices and examines progress towards the realization of a silicon based heterostructure technology. Target areas for further work are identified including: An enhanced understanding of metastable-growth processes; The need for defect confinement in discommensurate epitaxy; Elimination of manufacturing barriers caused by particulate induced defects in MBE and low growth rates in low temperature CVD.Over the last five years, studies of GexSi1−x have yielded an understanding of crystal growth mechanisms and information on electrical and optical properties such as bandstructure and heterojunction band alignment. These in turn lead to a number of preliminary device applications including optical detectors, modulation doped transistors and heterojunction bipolar transistors. In this paper, I will try to answer the question posed by the symposium organizers: In the germanium silicide system, has our understanding and experience reached the point that we have the basis for a technology, and if not, where must further work be done?
Structural Effects in Al(111)/Si(111) Heteroepitaxy by Partially Ionized Beam Deposition α
Authors: Yapsir A. S. , Choi C.-H. , Yang S. N. , Lu T.-M. , Madden M. , Tracy B. 
Published: March 2011

AbstractSingle crystal Al(111) films were grown on Si(111) surface at room temperature under a conventional vacuum condition using the partially ionized beam (PIB) deposition technique. The Al films were deposited with an ion to atom ratio of about 0.3% and an acceleration voltage of 1 kV. Transmission electron microscopy (TEM) analysis showed that the as-deposited films were single crystal with certain density of dislocation networks. These dislocations disappeared following a heat treatment at 450°C for 30 min. From X-ray diffraction and TEM patterns, it was observed that the Al(111) was aligned to the substrate with Al<1l0>//Si<1l0>. Possible mechanisms of the PIB epitaxial growth and a novel structural defect that is unique to this large lattice mismatch system are discussed.
Metastability in SiGe/Si Strained-Layer Structures
Authors: Dodson Brian W. 
Published: March 2011

AbstractThe physics governing growth and stability properties in SiGe/Si strainedlayer structures is reviewed. The role of metastability in crystal growth is outlined. Experimental data on stability limits and rates of strain relaxation are examined. We conclude that essentially all observations on relaxation of semiconductor strained-layer structures can be explained by standard models of plastic deformation adapted to the special conditions controlling dislocation dynamics in these structures.
Growth Studies of Heteroepitaxial Ge Films ON Si
Authors: Heim D.J. , Holesinger T.G. , Lakin K.M. , Shanks H.R. 
Published: March 2011

AbstractOne of the approaches to the growth of GaAs on Si substrates involves the use of a heteroepitaxial buffer layer such as Ge to reduce lattice mismatch. Recently, we have had success in growing heteroepitaxial Ge films on low temperature (∼275-500°C) Si substrates by the ionized cluster beam (ICB) technique. The design of a computer-controlled phase modulated ellipsometer for rapid monitoring of the initial stages of nucleation will be described. Ellipsometric data for single crystalline, polycrystalline and amorphous morphologies are reported.
Heteroepitaxy on (001) Silicon: Growth Mechanisms and Defect Formation.
Authors: Pirouz P. , Ernst F. , Cheng T. T. 
Published: March 2011

AbstractIn the growth of thin films of compound semiconductors on (001) silicon substrates by vapor deposition techniques, it is usual to employ a two-step process. In this method, an initial (buffer) layer is first grown at a relatively low temperature; once a continuous film has formed on the substrate, its temperature is raised for the subsequent bulk growth. Carrying out the growth in a one-step process by heating the substrate to the final temperature before allowing the gases into the CVD reactor usually results in a polycrystalline aggregate. In this paper, classical nucleation and growth mechanisms are used to explain-the reasons for the different morphology of the one-step and two-step growth films.The heteroepitaxial films on (001) silicon often contain a high density of stacking faults and twins. The occurrence of these planar defects is usually attributed to stresses that arise from lattice mismatch and/or thermal mismatch (differences in coefficients of thermal expansion) between the substrate and the epilayer. It is argued that, in fact, mismatch stresses play a minor role in the generation of planar defects. Instead, an alternative mechanism for their formation is proposed which is based on the facetted shape of nuclei and errors in stacking of {111} planes which occur during deposition on the facets.Conventional and high resolution transmission electron microscopy have been used to investigate three systems grown by CVD or MOCVD: SiC/Si, GaAs/Si and GaP/Si. These systems have different lattice and thermal mismatches, and the results support the proposed model for the formation of defects.
Multiphoton Excitation Techniques in Combustion Diagnostics
Authors: Goldsmith J. E. M. 
Published: March 2011

AbstractMultiphoton excitation provides spectroscopic access to several species that are very important in flame studies, but that cannot be detected in combustion environments using conventional optical techniques. This paper describes applications of multiphoton excitation techniques for detecting such species in combustion environments, with an emphasis placed on measurements of atomic hydrogen in flames.
Space Potential and Ion Energies in a Low Pressure Discharge Containing at least Two Negative Species
Authors: Ingram S G , Braithwaite N St J 
Published: March 2011

AbstractA Tonks-Langmuir type model for a one-dimensional low pressure (collisionless) plasma containing at least two species of Maxwellian negative charge carriers is examined. The solutions of this model yield the positive ion energy distribution at the sheath edge without needing to specify the ionization process. This distribution has a width consistent with the potential drop across the plasma, and is shown to satisfy the generalised Bohm criterion for sheath formation. However by assuming a form for the ionization rate in the plasma, the potential profile across the discharge has been calculated. It has been found that for a range of plasma parameters the solution for the potential at which quasineutrality fails becomes triple valued; the physical solution in this regime is identified.Many plasmas used for materials processing contain negative ions. It is important to understand how these ions influence the positive ion energy distribution at the substrate where the processing occurs.This work is also of relevance to the behaviour of Langmuir probes in electronegative plasmas.
Interferometry Techniques on Fusion Plasmas
Authors: Peebles W. A. 
Published: March 2011

AbstractOptical interferometry techniques allow phase changes in a medium to be accurately determined. Since plasmas introduce a phase modification proportional to electron density, interferometry has been used routinely to determine the time development of electron density profiles in magnetic confinement fusion plasmas. The present paper describes the basic principles of interferometry of plasmas and establishes criteria regarding wavelength selection, vibrational phase noise, phase averaging etc. In addition, recent advances at UCLA in interferometry of fusion plasmas will be described. For example, high spatial sampling has allowed the detailed study of MHD phenomena such as sawteeth and Mimov oscillations, and 2-D imaging interferometry has permitted tomographic reconstruction of electron density contours. Difficulties associated with interferometry on future fusion devices, such as CIT, will also be discussed together with possible solutions.
A Microwave Interferometer for Density Measurement and Stabilization in Process Plasmas
Authors: Pearson David I. C. , Campbell G. A. , Domier C. W. , Efthimion P. C. 
Published: March 2011

AbstractA low-cost heterodyne microwave interferometer system capable of measuring and/or controlling the plasma density over a dynamic range covering two orders of magnitude is demonstrated. The microwave frequency is chosen to match the size and density of plasma to be monitored. Large amplitude, high frequency fluctuations can be quantitatively followed and the longer-time-scale density can be held constant over hours of operation, for example during an inline production process to maintain uniformity and stoichiometry of films. A linear relationship is shown between plasma density and discharge current in a specific plasma device. This simple relationship makes control of the plasma straightforward using the interferometer as a density monitor. Other plasma processes could equally well benefit from such density control capability. By combining the interferometer measurement with diagnostics such as probes or optical spectroscopy, the total density profile and the constituent proportions of the various species in the plasma could be determined.