bluuebunny/crossref_metadata_2025_split huggingface dataset:
High-resolution microscopy and semiconductor interface structure
Authors: Gibson J. M. , Loretto D. 
Published: June 2020

The attainment of interpretable atomic-level resolution transmission electron microscopy in the last two decades has given rise to a flood of papers containing pictures of atoms in semiconductors in a variety of activities. This plethora of detail may leave the feeling in some that "if you"ve seen one atom, you’ve seen them all". The question is: how much information are we really getting from HREM of semiconductors? The answer is a lot: but nothing like as much as we believe. Furthermore, in many cases old-fashioned and pedestrian diffraction and diffraction contrast techniques can give more information, yet are little-applied. In this paper I will try to describe the applications of HREM which are promising, at the same time making no bones where other methods are better, or at least complementary.One important limit to the resolution of HREM images, which is most often overlooked, arises from the need for an acceptable signal-to-noise ratio. Every electron micrograph contains noise from a variety of sources: surface layers, photographic grains and electron shot noise.
Σ =13 tilt grain boundary in silicon bicrystal
Authors: Kim M.J. , Chen Y.L. , Carpenter R.W. , Barry J.C. , Schwuttke G.H. 
Published: June 2020

The structure of grain boundaries (GBs) in metals, semiconductors and ceramics is of considerable interest because of their influence on physical properties. Progress in understanding the structure of grain boundaries at the atomic level has been made by high resolution electron microscopy (HREM) . In the present study, a Σ=13, (510) <001>-tilt grain boundary in silicon was characterized by HREM in conjunction with digital image processing and computer image simulation techniques.The bicrystals were grown from the melt by the Czochralski method, using preoriented seeds. Specimens for TEM observations were cut from the bicrystals perpendicular to the common rotation axis of pure tilt grain boundary, and were mechanically dimpled and then ion-milled to electron transparency. The degree of misorientation between the common <001> axis of the bicrystal was measured by CBED in a Philips EM 400ST/FEG: it was found to be less than 1 mrad. HREM was performed at 200 kV in an ISI-002B and at 400 kv in a JEM-4000EX.
TEM characterization for material problems in silicon technology
Authors: Oppolzer H. , Cerva H. 
Published: June 2020

Continuing increase in integration density requires reduction of minimum feature sizes which have reached a level of 0.8 μm for the 4 Megabit dynamic random access memory (DRAM) and are approaching about 0.5 μm for the next generation DRAMs. The thickness of thin dielectrics will be in the nanometer range. Besides the dimensions of the small device structures also the properties of all involved materials have to be controlled carefully. Due to its capability of providing high-resolution imaging and analytical information material characterization by cross-sectional TEM is getting increasingly important during process development. Several examples related to various process steps will be presented.For the trench capacitor in 4 Mbit DRAMs thin dielectrics consisting of an SiO2-Si3N4-SiO2 triple layer are employed. While the thickness of the bottom oxide is reduced at the upper trench edge the nitride layer coats this edge uniformly since it is deposited from the vapor phase (Fig.1a). For the capacitor in a 64 Mbit memory cell oxide thicknesses of about 2 nm and 5 nm for the nitride will be required (Fig.1b).
Silicon layers grown over SiO2 by liquid phase epitaxy: Electron Microscopical study
Authors: Banhart F. , Phillipp F.O. , Bergmann R. , Czech E. , Konuma M. , Bauser E. 
Published: June 2020

Defect-free silicon layers grown on insulators (SOI) are an essential component for future three-dimensional integration of semiconductor devices. Liquid phase epitaxy (LPE) has proved to be a powerful technique to grow high quality SOI structures for devices and for basic physical research. Electron microscopy is indispensable for the development of the growth technique and reveals many interesting structural properties of these materials. Transmission and scanning electron microscopy can be applied to study growth mechanisms, structural defects, and the morphology of Si and SOI layers grown from metallic solutions of various compositions.The treatment of the Si substrates prior to the epitaxial growth described here is wet chemical etching and plasma etching with NF3 ions. At a sample temperature of 20°C the ion etched surface appeared rough (Fig. 1). Plasma etching at a sample temperature of −125°C, however, yields smooth and clean Si surfaces, and, in addition, high anisotropy (small side etching) and selectivity (low etch rate of SiO2) as shown in Fig. 2.
STEM characterization of short - Period GaAs-GaP strained superlattices
Authors: Ballesteros C. , Piqueras J. , Laknerb H. , Bollig B. , Ruiz A. , Briones F. 
Published: June 2020

In the epitaxial growth of superlattice (SL) structures composed of non lattice-matched materials a large difference in the lattice constants of the components could result in the formation of misfit dislocations at the interfaces. However, high quality structures can be obtained when the thickness of the layers are kept below a critical value and the difference is elastically accomodated by strain. In particular GaAs-GaP short period superlattices (3.7% mismatch) constitute an interesting case of strained SLS because the stress related shifts of the electronic levels can result in novel optical and electronic properties. In the present work the quality of GaAs-GaP SLS is studied by STEM.Short period GaAs-GaP superlattices were grown on SI (001) GaAs substrates by Atomic Layer Molecular Beam Epitaxy a new modification of the MBE technique capable of a sharp modulation of both group III and group V sources. To study the possibility of using the GaAs-GaP system for SL and Quantum Well structures a 18 monolayer thick GaAs quantum well was confined by two GaAs-GaP superlattices.
The dissociation of dislocations in SixGe1-x alloys
Authors: Stenkamp D. , Jäger W. 
Published: June 2020

The knowledge of the structure of dislocations in semiconductors is of importance for an understanding of their mechanical and electrical properties. In electronic devices dislocations are known to act as recombination centers for charge carriers and as traps for impurity atoms. In addition dislocations play an important role in the mechanical relaxation of elastic stresses in lattice-mismatched heterostructures. In Si-based epitactical heterostructures alloys of Si and Ge are used to adjust the lattice parameters by variation of the alloy composition thereby modifying the elastic stresses in a controlled manner. Such strained layer structures are of potential application for electronic components with improved performance.We have investigated dislocations in SixGe1-x crystals grown from the melt by the Czochralski and Bridgman method, respectively. The dissociation of dislocations into Shockley partials in SixGe1-x. alloys with low (x ≈ 0.05) and high (x ≈ 0.5) Si content was characterized by analytical electron microscopy at 300 kV.
TEM studies of pulse electrodeposited Cu-Se and CuInSe2 films
Authors: Veilleux G. , Boumerzoug M. , Saint-Jacques R.G. , Dao Lê H. 
Published: June 2020

Photovoltaic technology is considered as one of the major options for large-scale energy production without pollution. Thin-film technologies are seen as a potential approach to produce cost-effective electricity by photovoltaic. Among the different thin-film deposition techniques (CVD, vacuum evaporation, sputtering, etc.), electrodeposition has emerged as a low-cost method. Using a pulsed electrodeposition technique semiconductor thin films of Cu-Se and CuInSe2 with improved uniformity and lower impurity have been prepared. Varying the electrodeposition solution pH, stoichiometric CuSe, Cu3Se2, Cu2 Se and Cu2Se films on Indium Tin Oxide (ITO) coated glass or Ni electrodes were obtained. Their composition and properties varied with heat treatment (3).This paper reports the detailed study by Energy-Dispersive Spectrometry (EDS) and Transmission Electron Microscopy (TEM) of heat treatment effects on the composition and phase changes. EDS analyses were done on films deposited onto ITO glass using an Hitachi S-530 Scanning Electron Microscope (SEM). Cerac 99.99% pure powders were used to establish EDS calibration spectra. TEM studies were done on films directly deposited onto Ni grids. Selected area diffraction pattern (SADP) analyses were used to identify the structures. Samples were examined in a Philips EM-300 TEM operated at 100 kV.
Growth and microstructure of Cd1-xZnxS films deposited by hot-wall evaporation technique
Authors: Chaudhuri S. , Dhar A. , Pal A.K. 
Published: June 2020

Recent developments in the field of solar photovaltaic technology with CdS as window layer indicated that Cd1-x Znx S is more suitable as the window layer because its propeerties may be tailored by simply adjusting the Zn content. It is known that the band gap of (Cd, Zn) S increases linearly with increasing Zn in the film.We report here our studies on the growth and microstructure of thin films of cadmium zinc sulphide (Cd1-xZnxS) with the values of x in the range (0<x<0.27). Films were deposited by coevaporation of cadmium sulphide and zinc sulphide by the hot wall evaporation. Three different substrates (NaCl, KCl and LiF) were used for deposition of films in the thickness range 70 - 90 nanometer. The substrate, source and hot wall temperatures were 510 K, 1170 K and 480 K respectively.The microstructure of the films (fig. 1 ,2,3) were observed by transmission electron microscope (Hitachi H 600) and scanning electron microscope (Hitachi S-2300).
Electron Microscopy of CuInSe2 polycrystalline films
Authors: Albu-Yaron Ana , Margulis Lev , Hodes Gary , Noufi Rommel 
Published: June 2020

Despite the continuing interest in and research on CuInSe2 (CIS) as one of the prime candidate materials for thin film photovoltaics, there are still many gaps in the knowledge and understanding of this material. One area where there is still much to be learned is the microstructural properties of the CIS film and the effect of the substrate on these properties. Relatively few groups have studied these aspects. We have recently described an aggregate macrostructure and its component microstructure. Here we report on the microstructure of individual crystallites in the CIS films grown on different substrate materials.CIS films were evaporated using 3 separate sources onto heated (350-450°C) substrates of Mocoated (∼ 0.6 μm) Si single crystal, Al2O3 and 7059 Corning glass. For the transmission electron microscopy (TEM) examinations plan-view specimens were prepared by plasma or chemical etching. Cross-sections of the films deposited on Si single crystal slices were prepared by standard mechanical grinding and polishing followed by thinning to perforation by Ar+ ion bombardment. The specimens were examined by TEM using a Philips EM400T microscope operated at 120 kV. The obtained results show the following trends.
Cross-section preparation of copper/polyimide interfaces for TEM analyses
Authors: Csencsits Roseann , Riel Norman , Rose Jamie , Dion John 
Published: June 2020

Copper/polyimide (Cu/PI) structures are used extensively for computer packaging applications. For high circuit density multi-chip substrates, a thin film (typically 2-5μm) of polyimide is used; but the polyimide used to interconnect the multi-chip substrates via tape automated bonding (TAB) is typically 50μm thick to protect the tape leads from the cantilever effect. Although many spectroscopic, adhesion and deformation studies have been published about the bonding of metals to thin polyimide, relatively little has been published regarding the use of metal on thick polyimide.One factor limiting the analyses of these interfaces derived from the thick polyimide is the difficulty preparing adequate TEM specimens.Due to the greatly differing ion milling rates of metals and polymers, and the thickness of the two layers, a preparation technique was developed on model tape samples.The model samples consisted of 1μm sputtered Cu on 50μm polyimide, with and without Cr adhesion layers.
A novel TEM technique for junction delineation in integrated circuits
Authors: Romano A. , Vanhellemont J. , De Keersgieter A. , Vandervorst W. , Morante J. R. , Van Landuyt J. 
Published: June 2020

Ion implantation is a well established technique to dope selectively prespecified regions of silicon substrates. It has the drawback that a thermal treatment is required to activate the dopant and to reconstruct the crystal lattice. This leads to dopant diffusion in depth and also laterally, when the implantation has been preformed through a patterned mask.In this paper two different approaches to determine the doping profile using chemical etching and TEM are presented. Cross-section specimens are prepared using a technique described elsewhere, followed by preferential etching.The first approach is well established and is based on the combined action of HF and HNO3.Low concentrations of HF are used to keep the etching rate low enough. Figure 1 shows a cross-section of a boron implanted and annealed sample which has been etched using the solution HF(40%):HNO3(65%)= 1:300 at 5°C for 80 seconds. The etching rate is proportional to the doping level, as shown in figure 2 and it can be observed that the lowest level which one can delineate with this solution is of the order of 1017cm−3, which is in agreement with the delineated level of figure 1, namely 6·1017 cm−3.
Conventional methods of Lorentz microscopy
Authors: Geiss H.Roy 
Published: June 2020

Lorentz electron microscopy has been used to study magnetic domain/domain wall structures in thin films since 1959. Initially the contrast was described in terms of the classical Lorentz deflection of the incident electron beam. As a result Lorentz microscopy has become the general designation given to any of the techniques used to study the magnetic structure with electron beams. However, when sufficiently weak interactions are considered, a more rigorous quantum-mechanical description of the electron-specimen is required. It thus becomes necessary to consider the basis of magnetic imaging as following from the interaction between the magnetic vector potential of the specimen and the incident electron beam. This interaction results in a phase change of the propagating electron beam which is proportional to the path integral of the vector potential. Thus Lorentz microscopy, in reality, is simply phase contrast microscopy for a special class of objects.For many of the magnetic thin films investigated the coercivity of the film is so low that it must be in a nearly zero field environment in order to retain the domain structure. In order to achieve this condition experimentally, the objective lens is usually turned off and the diffraction lens is used as the image forming lens.
Fabrication and characterization - by High Resolution Electron Microscopy and atom probe microanalysis - of Co-based metallic multilayer films
Authors: Petford-Long Amanda K. , Cerezo A. , Hetherington M.G. 
Published: June 2020

The fabrication of multilayer films (MLF) with layer thicknesses down to one monolayer has led to the development of materials with unique properties not found in bulk materials. The properties of interest depend critically on the structure and composition of the films, with the interfacial regions between the layers being of particular importance. There are a number of magnetic MLF systems based on Co, several of which have potential applications as perpendicular magnetic (e.g Co/Cr) or magneto-optic (e.g. Co/Pt) recording media. Of particular concern are the effects of parameters such as crystallographic texture and interface roughness, which are determined by the fabrication conditions, on magnetic properties and structure.In this study we have fabricated Co-based MLF by UHV thermal evaporation in the prechamber of an atom probe field-ion microscope (AP). The multilayers were deposited simultaneously onto cobalt field-ion specimens (for AP and position-sensitive atom probe (POSAP) microanalysis without exposure to atmosphere) and onto the flat (001) surface of oxidised silicon wafers (for subsequent study in cross-section using high-resolution electron microscopy (HREM) in a JEOL 4000EX. Deposi-tion was from W filaments loaded with material in the form of wire (Co, Fe, Ni, Pt and Au) or flakes (Cr). The base pressure in the chamber was around 8×10−8 torr during deposition with a typical deposition rate of 0.05 - 0.2nm/s.
Microdomains in BaFeO3-y (0.35 < y < 0.50)
Authors: Vallet-Regí M. , Parras M. , González-Calbet J.M. , Grenier J.C. 
Published: June 2020

BaFeO3-y compositions (0.35<y<0.50) have been investigated by means of electron diffraction and microscopy to resolve contradictory results from powder X-ray diffraction data.The samples were obtained by annealing BaFeO2.56 for 48 h. in the temperature range from 980°C to 1050°C . Total iron and barium in the samples were determined using chemical analysis and gravimetric methods, respectively.In the BaFeO3-y system, according to the electron diffraction and microscopy results, the nonstoichiometry is accommodated in different ways as a function of the composition (y):In the domain between BaFeO2.5+δBaFeO2.54, compositional variations are accommodated through the formation of microdomains. Fig. la shows the ED pattern of the BaFeO2.52 material along thezone axis. The corresponding electron micrograph is seen in Fig. 1b. Several domains corresponding to the monoclinic BaFeO2.50 phase, intergrow with domains of the orthorhombic phase. According to that, the ED pattern of Fig. 1a, can be interpreted as formed by the superposition of three types of diffraction maxima : Very strong spots corresponding to a cubic perovskite, a set of maxima due to the superposition of three domains of the monoclinic phase along [100]m and a series of maxima corresponding to three domains corresponding to the orthorhombic phase along the [100]o.
Crystallization in highly irradiated poly(vinyl chloride)
Authors: Avalos-Borja M. , Adem E. , Cota L. , Burillo G. 
Published: June 2020

Poly (vinyl chloride) is one of the most widely used materials in today’s society, and the study of its properties is relevant to many fields. In the present case, we investigate changes that occured in this material when it was exposed to high doses of gamma rays. Previous studies using electron beam irradiation indicated the possibilities of using this material as a “getter” due to its ability to capture gases like CO2 and CO. The present work deales with preliminary results on the structural characteristics of a carbon rich material obtained using ionizing radiation.Radiation treatment was done in several steps, a) irradiation of 1000 Mrad (at dose rate of 0.95 Mrad/hr) in a Gamma Beam Type 651-PT ( Co) source. b) the sample is then extracted with tetrahydrofuran (THF) in order to separate the homopolymer from the gel that was formed during irradiation. c) the gel fraction (crosslinked polymer) was filtered, dried and weighted, and exposed again for 200 Mrad more
Low-energy displacement damage and the effect on the AEM of Ceramics
Authors: Howitt D. G. , Medlin D.L. , Cluckie M. M. 
Published: June 2020

The observation that the signal from light elements such as carbon, oxygen, and nitrogen decreases in strength with time is to be expected for displacement in ceramic materials at high voltage, not only because the momentum transfer from an electron is more favorable, but also because the lattices are often full of defects. Even though the sensitivities of these materials can be below that of close parked metals at high voltage, during analytical electron microscopy the beam currents are sufficiently intense that the effect can be substantial. The loss rates for the signal are however quite predictable in the early stages and need not interfere with quantitative assessments of composition.An example of the loss of carbon signal from titanium carbide is shown in Figure 1 and a determination of the overall cross-section for carbon loss at 100 keV indicates a value close to 0.3 barns. This is about the cross-section for carbon displacement at 20 eV which is a conservative estimate of the binding energy for carbon in the lattice. Early experiments on vanadium carbide (Venables, 1969) indicate a similar overall cross-section however the threshold energy for the electrons to induce the damage is about only 5 eV. These results are consistent with the transfer of about 5 eV from an incident electron inducing a very small displacement of the carbon atom, of the order of an interatomic distance, with a damage cross-section of about 200 barns. Since the process needs to be repeated several times before the carbon atom is lost from the specimen the measured cross-section is proportionality reduced.
New method for producing double replica for observing and a precipitates
Authors: Spiradek Krystyna , Czyrska-Filemonowicz Aleksandra , Hörl Erwin M. 
Published: June 2020

In metallurgy and metal physics it is very often necessary to analyse the types, shapes, sizes etc. of precipitates in a metal or metal alloy. Furthermore it is often of importance to know the distribution of these particles along the grain boundaries and within the grains. For this analysis a new EM technique has been developed.The procedure of this technicue is the following:First of all specimens are prepared of the materials to be investigated in such a way that one obtains thin metal plates or foils of a thickness of 0,1 to 0,01 mm. This foils are etched in a H2O solution of 10 % H2CrO3 for revealing the surface structure. Afterwards carbon is avaporated on both sides of the foils. In the next step a square grid of 3 mm х 3 mm is scratched into the foil on both sides in such a way that the grid of the top side is exactly positioned over the grid of the bottom side. After this procedure the specimens are inserted into an ethanol solution of 10 % bromine in a horizontal position till the metallic matrix is solved and the precipitates are left. This step takes approx. 24 hours. Afterwards the replicas consisting of the two carbon layers with the precipitates between them are cleaned using firstly ethanol afterwards 50% ethanol in destilled water and finally just destilled water (.5 hours in each bath). In the next step the replicas are put on EM grids of sandwich type. Great care is necessary in this step in order to avoid shifting of the carbon layers and disturbances of the positions of the precipitates. These replicas are now ready for TEM as well as SEM investigations, as soon as they are dry.
Characterization of active slip systems in Hg0.8Cd0.2Te
Authors: McKeagney D. B. , Campbell T. J. 
Published: June 2020

The compound semiconductor Hg0.8Cd0.2Te is commonly used in the production of infrared detection devices. In bulk growth, due to low Hg-Te bond strengths, high dislocation densities are often encountered. These dislocations, which are generated during the crystal growth process, significantly impair the performance of the semiconductor device. To best control this dislocation generation during growth, a knowledge of the active slip systems within the crystal lattice is desirable.Microhardness tests were performed on two distinct crystal surfaces of Bridgman grown Hg0.8Cd0.2Te crystals. Selected area electron channeling was used to determine trie crystallographic orientations of the surfaces that were tested. The slip lands that were introduced during the indentation process were observed using both the scanning electron and optical microscopes. From the data obtained, using elementary crystallographic techniques, the dominant slip systems active in Hg0.8Cd0.2Te were characterized.