bluuebunny/crossref_metadata_2025_split huggingface dataset:
TEM studies of spots crystallized in amorphous films by electron beam
Authors: Kolosov V. Yu. 
Published: June 2020

Electron beam (e-beam) annealing is powerful method for local modifying and crystallization in desired modes of semiconductors and microelectronics components and is also interesting for information storing. Nevertheless, discussed in many papers mechanism of explosive crystallization of amorphous (a-Ge, a-Si) films is still not clear enough and requires new structure studies. It is more relevant for recently discovered growing of micro-crystals with strong internal lattice bending (gradient crystals) in some amorphous films. This paper reports our findings in the structure of spots crystallized in these unusual modes by TEM beam in vacuum deposited (Ge, Se, Se-Te) or prepared by pyrolysis (Fe2O3) unsupported amorphous films. Bendcontour technique was used to analyze the fields of lattice orientation for gradient crystals, including in situ crystal growth studies or videorecord analysis.Explosively crystallized spots in a-Ge, a-Si films are known to consist of 3 zones, Fig. 1. We observed the same zones for films 400-800Å thick, deposited at rates 1- 100Å/s: polycrystal central zone (O), surrounded by a fan of radially elongated single crystals (zone R) which in turn is surrounded by zone (C), formed by concentric or spiral shells (each subdivided into single-crystal subshell and polycrystal subshell).
Replica observation by transmission electron microscopy of GaAs surface grown on vicinal Si (001)
Authors: Inoue T. , Kikuchi Y. , Sasaki T. , Eshita T. , Yoshida M. 
Published: June 2020

Over the past several years, heteroepitaxy of GaAs on Si substrates has received strong interest because of its potential for monolithic integration of GaAs optical devices with Si integrated circuit technology. For heteroepitaxy of GaAs on Si substrate, Si(001) substrates oriented toward [110] by a few degrees (1) are used, therefore the GaAs epitaxial layer is expected to have a stepped surface. In this study, we characterized the GaAs surface, grown on vicinal Si(001 ) substrates, by replica observation using transmission electron microscopy (TEM).The Si substrates were oriented 2 degrees off towards [110] and their surface was expected to have a regular array of [110] steps, 8 nm apart. A two-step growth process (1) was employed to grow GaAs on Si(001) by metalorganic chemical vapor deposition (MOCVD). The Ga source was trimetyl gallium (TMG) and As source was AsH3. Following 10 minutes of 1000°C heat treatment in a H2, gas flow to remove the native oxide, 20 nm GaAs buffer layers were grown at 450°C. They were then heated to a growth temperature of 650°C to grow the GaAs epitaxial layers an additional 3 μm.
HREM of low-temperature InP grown by gas source MBE
Authors: Rajesh R. , Kim M.J. , Bow J.S. , Carpenter R.W. , Maracas G.N. 
Published: June 2020

In recent times, following the application of MBE GaAs grown at low temperatures as an electrical buffer layer in field effect transistors, there has been a focus of attention on other III-V materials grown at low temperatures. This lead to speculation on the possibility of applications of low temperature (LT) InP in electronic and photonic devices resulting in a need to correlate the structural properties of this material with the electrical and optical measurements. The current endeavour is directed toward studying the structure and the morphology of LT InP synthesized under varying growth conditions in order that a correlation with properties like conductivity and photoluminescence can be effected.In this present study, InP grown at low temperatures by gas source MBE using for sources solid indium and P2 has been characterized by TEM. Samples were prepared by mechanical grinding, dimpling and low-angle argon ion-milling. The low-angle technique was employed because it greatly mitigates the formation of indium islands during the milling of InP samples with Ar+ ions. Observations were made on an ISI 002B electron microscope, operating at 200 kV.
Formation of defects in boron-implanted PEPBLT structures
Authors: David Theodore N. , Sundaram Sam , Fejes Peter 
Published: June 2020

Variations on LOCOS (local-oxidation of silicon) are being explored for device-isolation, to implement further miniaturization of VLSI devices. One such variation involves poly-encapsulated poly-buffered LOCOS + trench-isolation (PEPBLT). The method provides a means to support device scaling and to create self-aligned shallow field-oxide elements with minimal encroachment into active regions. In an earlier study, dislocations were observed to be associated with a combination of high-dose ∼1E15 cm−2 phosphorus implants and PEPBLT isolation. The present study investigates the effect of boron implants on similar PEPBLT structures. The effect of fabrication-related stresses in the structures is of interest because extended-defects, if formed, could electrically degrade transistors.PEPBLT structures were exposed to varied processing conditions to build high-performance bipolar transistors. Isolated active-device regions from the above structures were characterized using TEM. Some of the active regions were (i) implanted with 80 keV-8.5E15 cm−2 boron with no anneal, (ii) implanted with 80 keV- 8.5E15 cm−2 boron and annealed at 900°C/90’/N2 plus 1050°C/30” RTA during the course of processing, (iii) not implanted.
Geometry-dependence of defects in PBLT serpentines
Authors: Fejes Peter , David Theodore N. , Liang Han-Bin 
Published: June 2020

Poly-buffered LOCOS + trench-isolation is a technique being explored for device-isolation on semiconductor substrates. The method creates self-aligned shallow field-oxide elements with minimal encroachment into active regions. In an earlier study/dislocations were observed in PBLT structures, associated with a combination of high-dose [∼1E15 cm−2] phosphorus implants and PBLT isolation. The present study investigates the effect of implant- and isolation-geometries on the formation of extended-defects in PBLT structures. The effect of fabrication-related stresses in the structures is of interest because extended-defects, once formed, can electrically degrade devices.PBLT structures were fabricated using varied implant- and isolation- geometries. Selected regions of the structures were exposed to 1E15 cm−2 phosphorus implants. Transmission electron microscopy was then used to characterize these regions. Some of the structures investigated were (i) trench with no adjacent implant, (ii) trench with an adjacent trench, but no implant, (iii) trench with a 1E15 cm−2 phosphorus implant placed ∼4 μm from the trench, (iv) trench with a 1E15 cm−2 phosphorus implant placed ∼2 μm from the trench, (v) doubly-kinked trench with a 1E15cm−2 phosphorus implant placed between the kinks.
TEM/AFM correlative studies of thin-film metallization
Authors: David Theodore N. , Sharma Renu , Carrejo Juan 
Published: June 2020

Since the invention of AFM (atomic force microscopy) applications of the technique have grown from year to year. It is expected that with time, there will be an increased use of AFM in the semiconductor industry for analysis of surface-topography and microstructure of thin films and heterostructures. However, before the technique can be used on its own for analyzing the behavior of thin films, it is necessary to establish legitimate areas of application of the technique. The present study uses AFM and TEM (transmission electron-microscopy) to study a few examples of thin-film metallizations and then looks at the extent of correlation between the two. It turns out that TEM and AFM work very well as complementary techniques. Caution is required in interpreting AFM micrographs.As examples of metallization Al(Cu), polysilicon and TiW thin films were investigated using AFM and TEM. Al(1.5%Cu) films were sputtered onto SiO2/Si substrates for ∼1 second (unbiased) at a substrate temperature of 450°C.
Structural and compositional effects on the electron migration properties of Al-Cu alloy
Authors: Liu J.B. , Duan J.Z. , Gronsky R. 
Published: June 2020

Aluminium and aluminium-based alloys are typically used as the metallization interconnections in LSI and VLSI silicon-based integrated circuits. Important factors affecting the lifetime and reliability of these interconnections in IC devices are the individual microstructures, device layer combinations, electron migration, and stress migration that occur during their fabrication and their in-service application. There are many possible remedies for each of these factors. The use of bias sputtering or “planarization” has been shown to improve the quality of the interconnection greatly. Recently, some studies have revealed a new planarization technique involving sputter deposition of Al alloys at elevated temperature without any substrate bias, combined with a TiN precoating to reduce the migration of Al atoms. In this paper, the microstructure of Al-0.2Cu/TiN/SiO2/Si under optimum lifetime conditions is assessed, and a mechanism of void formation is proposed to explain the observations.A representative TEM cross section image of Al-0.2% Cu sputtered at 100 V bias and at substrate temperature 450°C with a TiN/SiO2 prercoating is shown in Fig.l. The surface topography of the Al-Cu alloy is shown for comparison purposes in Fig.2.
The observation of defects on (100) CdTe surfaces by chemical etching
Authors: Lee M.E. 
Published: June 2020

The crystalline perfection of bulk CdTe substrates plays an important role in their use in infrared device technology. The application of chemical etchants to determine crystal polarity or the density and distribution of crystallographic defects in (100) CdTe is not well understood. The lack of data on (100) CdTe surfaces is a result of the apparent difficulty in growing (100) CdTe single crystal substrates which is caused by a high incidence of twinning. Many etchants have been reported to predict polarity on one or both (111) CdTe planes but are considered to be unsuitable as defect etchants. An etchant reported recently has been considered to be a true defect etchant for CdTe, MCT and CdZnTe substrates. This etchant has been reported to reveal crystalline defects such as dislocations, grain boundaries and inclusions in (110) and (111) CdTe. In this study the effect of this new etchant on (100) CdTe surfaces is investigated.The single crystals used in this study were (100) CdTe as-cut slices (1mm thickness) from Bridgman-grown ingots.
CVD process characterization using a selective delineation technique for quantitative SEM analysis
Authors: McAfee George H. , Dean Steven J. 
Published: June 2020

The scanning electron microscope is one of the most universal and well-respected analytical tools in the semiconductor industry. The limitless potential of this tool serves as the basis for this article. As process geometries continue to shrink below the sub-micron level, precise characterization of the individual processing areas is of the utmost importance. One area of particular interest is the CVD (chemical vapor deposition)/thin film area.Modern CVD reactors implement a triple injector configuration for film deposition. Each injector provides an individual contribution to the composite film thickness. In essence, the composite film is comprised of three separate thin film layers. These films have a very high surface tension and the interfaces of the three films form areas of high stress. From these two properties, surface tension and interfacial stress, it becomes possible to quantify and visually identify the individual contribution of each injector (in a multi-injector CVD reactor). This can be accomplished by using a selective etching technique in preparation for cross-sectional SEM analysis. Areas of high stress, by nature, have a higher etch rate than the bulk film itself.
Direct phase determination in electron crystallography: layer silicates
Authors: Dorset Douglas L. 
Published: June 2020

Recently the direct 3D determination of an aluminosilicate structure was reported based on high-voltage, high resolution electron microscopy of thin slices representing several projections of the crystal. It was particularly interesting that the relatively light oxygen atom positions could be visualized along with those of heavier components (Al, Si, Fe) in the staurolite structure.Although this direct visualization of a crystal structure in the electron microscope certainly is a tour de force, representing a significant advance in microscopic instrumentation and technique, the electron crystallography of silicate structures at atomic resolution is, in itself, not particularly a new field of investigation. For example, in his book, B. B. Zvyagin outlines how he was able to use texture electron diffraction intensity data from several layer silicates in order to determine their crystal structures via interpretation of the Patterson function or construction of reasonable layer models suggested by the atomic stoichiometry.It is unfortunate that many of the early Russian electron diffraction structure analyses have been overlooked or even ignored by the crystallographic community.
Least-square refinement of structure parameters from CBED integrated intensities: application to determination of temperature factors in Y BA2CU3O7
Authors: Gjønnes Kjersti , Gjønnes Jon 
Published: June 2020

Electron diffraction intensities can be obtained at large scattering angles (sinθ/λ ≥ 2.0), and thus structure information can be collected in regions of reciprocal space that are not accessable with other diffraction methods. LACBED intensities in this range can be utilized for determination of accurate temperature factors or for refinement of coordinates. Such high index reflections can usually be treated kinematically or as a pertubed two-beam case. Application to Y Ba2Cu3O7 shows that a least square refinememt based on integrated intensities can determine temperature factors or coordinates.LACBED patterns taken in the (00l) systematic row show an easily recognisable pattern of narrow bands from reflections in the range 15 < l < 40 (figure 1). Integrated intensities obtained from measured intensity profiles after subtraction of inelastic background (figure 2) were used in the least square fit for determination of temperature factors and refinement of z-coordinates for the Ba- and Cu-atoms.
Cluster analysis for large data sets: applications to individual aerosol particles from the mid-pacific
Authors: Shattuck Thomas W. , Anderson James R. , Tindale Neil W. , Buseck Peter R. 
Published: June 2020

Individual particle analysis involves the study of tens of thousands of particles using automated scanning electron microscopy and elemental analysis by energy-dispersive, x-ray emission spectroscopy (EDS). EDS produces large data sets that must be analyzed using multi-variate statistical techniques. A complete study uses cluster analysis, discriminant analysis, and factor or principal components analysis (PCA). The three techniques are used in the study of particles sampled during the FeLine cruise to the mid-Pacific ocean in the summer of 1990. The mid-Pacific aerosol provides information on long range particle transport, iron deposition, sea salt ageing, and halogen chemistry.Aerosol particle data sets suffer from a number of difficulties for pattern recognition using cluster analysis. There is a great disparity in the number of observations per cluster and the range of the variables in each cluster. The variables are not normally distributed, they are subject to considerable experimental error, and many values are zero, because of finite detection limits. Many of the clusters show considerable overlap, because of natural variability, agglomeration, and chemical reactivity.
Accuracies associated with the automated electron probe analysis of particulate populations
Authors: Small John A. , Calderone Matthew A. 
Published: June 2020

The analysis of large numbers of particles by automated scanning electron microscopy/ electron probe (ASEM) has been used in conjunction with multivariate analysis algorithms to classify atmospheric particles into different groups based on size, shape, and elemental composition. These groups or clusters and the number of particles belonging to each are often used to develop source apportionment for the sampled aerosol.There are several limitations particularly with the compositional analysis aspects of the automated routines that may limit the information that can be obtained from the sample. One of the major limitations of ASEM analyses is associated with the relatively short counting times, typically between 10-30 s, used for the accumulation of x-ray spectra from the individual particles. In contrast, the counting times used for conventional electron probe analyses are on the order of 5 minutes.We are conducting a series of experiments to study the effects of accelerating voltage, and electron dose (beam current, and counting time) on the accuracy, precision, and detection limits of ASEM analyses. The degradation of accuracy, precision and detection will have a pronounced effect on the separation of particles with similar but different elemental compositions into groups.
Near IR multichannel Raman spectroscopy with μm spatial resolution
Authors: Barbillat J. , Roussel B. 
Published: June 2020

The techniques and capabilities of near infrared (NIR) multichannel microprobing are described in detail in this paper.The advantages and drawbacks of various kinds of instruments used to measure Raman spectra excited in the NIR spectral range have been extensively studied and compared. We demonstrate that a dispersive spectrometer specially designed to match the recently improved NIR multichannel detectors (silicon-based CCD,Germanium and InGaAs photodiode arrays) may provide better results than a Fourier Transform Interferometer in two fields:- spatial resolution close to the diffraction limit in a micro-Raman confocal configuration (1.5 to 2 μm) and- extension of the Raman spectrum to the low-frequency region (Stokes and Anti-Stokes).Moreover, to observe the excitation profiles of both resonance and fluorescence, a combined multichannel instrument covering the entire range from 0.4 to 1.5 μm enables the user to select the best conditions of measurement.For the study of very small samples (close to the diffraction limit),it is optically impossible to fill in the wide entrance aperture of the interferometer with the image of the sample while covering correctly the optical elements inside the interferometer.
A high-throughput confocal Raman microprobe based on a single grating spectrograph and CCD detector
Authors: Adar Fran 
Published: June 2020

The availability of sharp cut-on holographic notch filters has enabled the design of simplified, compact Raman instruments for many applications where the size, complexity, and/or cost of instrumentation has been a significant limiting factor. With such a filter, a confocal Raman microprobe has been constructed around a 0.5 m focal length monochromator and 1” CCD detector. This system provides all the microprobe capabilities of the larger systems, including full confocal aperturing with spatial resolution determined by diffraction limitations. Since the gratings are kinematically mounted and easily interchangeable, the choice of grating will determine the trade-off on the array between spectral coverage and spectral resolution for any excitation wavelength between 400 and 830 nm.The practical usefulness of the system as a confocal Raman microprobe will be determined by the low frequency cut-off and the acquisition times. The low frequency cut-off will depend on the notch filter; at laser wavelengths shorter than 550nm the cut-off today is about 100-200 cm-1.
Raman mapping and imaging using microline focus spectromety (MiFS)
Authors: Gardiner Derek J. , Bowden Michael 
Published: June 2020

Early attempts to obtain Raman images relied upon illuminating the whole field of view with laser light, wavelength selecting the scattered light and imaging it onto a vidicon type TV detector. This method had several limitations, principally with sensitivity and inability to deal with fluorescence interference. Improvements have been made to this general approach, by the use of interference filters to select the required portion of the Raman spectrum for specific images and the possibilities of using Hadamard transform spectroscopy to produce micro-Raman images have been explored. Alternatively, the advantages of the single point micro Raman instrument can be retained and the sample moved under the focussed beam, either manually or by computer control, and the resulting spectroscopic data processed to generate the required map, image or profile.The development of cooled, slow scan, charge coupled device (ccd) detectors offers the possibility of using a line focus arrangement to reduce greatly the data collection times. Raman Microline Focus Spectroscopy (MiFS) utilises a line focussed Raman microscope coupled to a non-astigmatic spectrograph operating with a slow scanned ccd detector.
Spatially resolved Raman and photolumtnescence spectroscopy of advanced materials
Authors: Ager Joel W. , Rosenblatt Gerd M. 
Published: June 2020

We have developed and previously described a technique to profile important physical and chemical properties of materials based upon simultaneous acquisition of optical spectra excited along a laser-illuminated line, coupled with extensive and rapid spectral analysis to extract the desired informatioa Changes in materials properties that change the position, width, or relative intensities of spectral features can be mapped rapidly with a spatial resolution approaching 5 μm. Recently, we have used a combination of profiling photoluminescence (PL) spectroscopy and Raman scattering (RS) to measure bandgap and compositional variations in GaxIn1-xP epilayers grown on GaAs by organometallic vapor phase epitaxy (OMVPE). The spectral resolution in these experiments was 1 meV for PL and 0.4 cm-1 for RS; the spatial resolution was 85 μm.GaxIn1-xP has potential as a component of high-efficiency visible LED's and lasers (300 K bandgap of 2.26 eV at x = 0.74). It can be grown lattice matched to GaAs at x=0.51 (bandgap = 1.91 eV) by a variety of techniques. However, small variations in x cause misfit strain at the interface, making high-quality, low-defect material difficult to grow.
Forensic applications of IR infrared microscopic internal reflection spectroscopy
Authors: Bartick Edward G. , Reffner John A. 
Published: June 2020

Since the introduction of commercial Fourier transform infrared (FTIR) microscopic systems in 1983, IR microscopy has developed as an important analytical tool in research, industry and forensic analysis. Because of the frequent encounter of small quantities of physical evidence found at crime scenes, spectroscopic IR microscopes have proven particularly valuable for forensic applications. Transmittance and reflectance measurements have proven very useful. Reflection-absorption, specular reflection, and diffuse reflection have all been applied. However, it has been only very recently that an internal reflection (IRS) objective has been commercially introduced.The IRS method, also known as attenuated total reflection (ATR), has proven very useful for IR analysis of standard size samples. The method has been applied to adhesive tapes, plastic explosives, and general applications in the analysis of opaque materials found as evidence. The small quantities or uncontaminated areas of specimens frequently found requiring forensic analysis will often be directly applicable to microscopic IRS analysis.