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Showing papers on "Transmission electron microscopy published in 1988"


Journal ArticleDOI
TL;DR: X-ray diffraction and electron microscopy data are consistent with a structure of alternating perovskite and Bi-Ca-Sr-Cu-O layers, which reveals a b-axis superstructure of 27.2 A, numerous stacking faults, and other defects.
Abstract: Four phases are observed in superconducting Bi-Ca-Sr-Cu-O samples. The superconducting phase, with onset temperature near 120 K, is a 15.4-A-layered compound with composition near Bi2Ca1Sr2Cu2O9 and an A-centered orthorhombic unit subcell 5.41 x 5.44 x 30.78 A. X-ray diffraction and electron microscopy data are consistent with a structure of alternating perovskite and Bi2O2 layers. High-resolution transmission electron microscopy images reveal a b-axis superstructure of 27.2 A, numerous (001) stacking faults, and other defects.

500 citations


Journal ArticleDOI
TL;DR: The defect structure of lattice mismatched 1 −μm InxGa1−xAs (x≊012, misfit Δa/a≊85×10−3) epilayers on GaAs was studied with scanning cathodoluminescence (CL), transmission electron microscopy (TEM), highvoltage electron microscope (HEM), and scanning electron microscope (SEM) as mentioned in this paper.
Abstract: The defect structure of lattice‐mismatched 1‐μm InxGa1−xAs (x≊012, misfit Δa/a≊85×10−3) epilayers on GaAs was studied with scanning cathodoluminescence (CL), transmission electron microscopy (TEM), high‐voltage electron microscopy, and scanning electron microscopy CL shows that nonradiative recombination lines exist in the GaAs buffer layer as far as 4000 A from the interface The density of these defects is independent of substrate dislocation density Plan‐view TEM analysis indicates that the majority of these dislocations in the buffer layer are sessile edge half‐loops Cross‐sectional TEM shows that loops also extend into the InGaAs epilayer, but the majority of the loops are located on the buffer layer (substrate) side of the interface A model is proposed to explain sessile edge dislocation formation in the buffer layer A comparison of CL and high‐voltage electron microscopy images from the same interface area reveals that the dark nonradiative recombination lines seen in scanning luminescence i

177 citations


Journal ArticleDOI
L. X. He1, Y.K. Wu1, K. H. Kuo1
TL;DR: In this article, the authors present results par microscopie electronique en transmission et diffraction electronique a aire selectionnee ou en faisceau convergent.
Abstract: Presentation des resultats par microscopie electronique en transmission et diffraction electronique a aire selectionnee ou en faisceau convergent

175 citations


Journal ArticleDOI
TL;DR: In this paper, a rapid analytical technique was developed for obtaining the reduced density function, G(r), from polycrystalline and amorphous thin films, using post-specimen scanning and an energy loss spectrometer on a transmission electron microscope.
Abstract: A rapid analytical technique has been developed for obtaining the reduced density function, G(r), from polycrystalline and amorphous thin films, using post-specimen scanning and an energy loss spectrometer on a transmission electron microscope. The technique gives on-line analysis of nearest-neighbour distances to an accuracy of 0.02 A, together with coordination numbers. It has the advantage over X-ray and neutron techniques that the information can be obtained from small (≲ 1 μm diameter) chosen regions of the specimen. Results from neighbouring selected regions can be compared.

164 citations


Journal ArticleDOI
TL;DR: In this paper, a transition state model describing the motion of grain boundaries during ion bombardment has been applied to the present experimental data, which suggests that bombardmentenhanced grain growth may be due to thermal migration of bombardmentgenerated defects across the boundary.
Abstract: Grain growth has been studied in polycrystalline thin films of Ge, Si, and Au during ion bombardment. The phenomenon has been characterized by varying the ion dose, ion energy, ion flux, ion species, substrate temperature, and thin‐film deposition conditions. Films bombarded with Si+, Ar+, Ge+, Kr+, and Xe+ exhibited enhanced grain growth which was weakly temperature dependent and proportional to the energy deposited in elastic collisions at or very near grain boundaries. The effect of these parameters on grain size and microstructure was analyzed both qualitatively and quantitatively using transmission electron microscopy. A transition state model describing the motion of grain boundaries during ion bombardment has been applied to the present experimental data. The results suggest that bombardment‐enhanced grain growth may be due to thermal migration of bombardment‐generated defects across the boundary. The calculated defect yield per incident ion was found to be directly related to enhanced grain growth...

122 citations


Journal ArticleDOI
22 Apr 1988-Science
TL;DR: A link between scanning tunneling microscopy (STM) and conventional transmission electron microscopy has been established for biological material by applying STM on freeze-dried recA-DNA complexes coated with a conducting film as discussed by the authors.
Abstract: A link between scanning tunneling microscopy (STM) and conventional transmission electron microscopy has been established for biological material by applying STM on freeze-dried recA-DNA complexes coated with a conducting film. The topography of the complexes observed by means of STM revealed a right-handed single helix composed of about six recA monomers per helical turn.

117 citations


Journal ArticleDOI
TL;DR: In this article, high-Tc (105 K) and low Tc (75 K) superconducting oxides were examined by transmission electron microscopy with an EDX analysis.
Abstract: Both high-Tc (105 K) and low-Tc (75 K) superconducting oxides recently reported by Maeda et al. (Jpn. J. Appl. Phys.: in press) are examined by transmission electron microscopy with an EDX analysis. The chemical compositions are estimated to be Bi4Sr3Ca3Cu6Ox and Bi4Sr3Ca2Cu4Oy for high- and low-Tc samples. The diffraction patterns and high-resolution structure images show that the compounds have layered structures with alternate Bi2O2 layers and perovskite ones in a c-direction. A high-resolution image projected along the a-axis clearly shows the presence of the modulated structure with lattice curving.

111 citations



Journal ArticleDOI
TL;DR: In this paper, the nature of extended defects in silicon introduced by hydrogen containing plasmas has been studied by transmission electron microscopy for a variety of technological processes, including planar defects, gas bubbles, and a heavily damaged near surface region.
Abstract: The nature of extended defects in silicon introduced by hydrogen containing plasmas has been studied by transmission electron microscopy for a variety of technological processes. Depending on the doping level of the substrate, the substrate temperature and the presence/absence of simultaneous energetic ion bombardment, {111} planar defects, gas bubbles, and a heavily damaged near‐surface region have been observed.

89 citations


Journal ArticleDOI
TL;DR: In this article, various characteristics of these thin polycrystalline superconductor films are discussed and the effectiveness of the zirconia buffer layer in preventing interdiffusion is investigated.
Abstract: Thin films of the high‐temperature superconductor Y‐Ba‐Cu‐O with zero‐resistance transition temperatures up to 83 K have been recently reported by using a zirconia buffer layer on the primary materials of interest for electronics, Si and SiO2. In this letter, various characteristics of these films are discussed. Microstructural analysis using transmission electron microscopy shows the complex morphology of the unoriented polycrystalline films. Elemental depth profiling by x‐ray photoelectron spectroscopy shows the effectiveness of the zirconia buffer layer in preventing interdiffusion; fluorine is found throughout the film at an abundance of 4 at. % The critical current density was measured as a function of temperature; its value is 5 kA cm−2 at 4.2 K.

77 citations


Journal ArticleDOI
S Kashida1, J Akai1
TL;DR: In this article, a simplified structural model is presented for the arrangement of vacant copper sites; the vacancies occupy the 312/*31/2 units in the (111)c basal planes, and these vacancy layers are stacked every four copper layers, forming a ladder-like structure.
Abstract: The structural phase transition of cuprous selenide has been studied by means of X-ray diffraction, electron diffraction and high-resolution transmission electron microscopy. The room-temperature phase is pseudo-monoclinic (a=c=7.14 AA approximately=1/2ac(112), b=81.9 AA approximately=8ac(111) and beta =120 degrees , where ac is the lattice constant in the high-temperature cubic phase). The structure is characterised by a periodic array of vacant tetrahedral and nearby interstitial copper atoms. A simplified structural model is presented for the arrangement of vacant copper sites; the vacancies occupy the 312/*31/2 units in the (111)c basal planes, and these vacancy layers are stacked every four copper layers, forming a ladder-like structure.

Journal ArticleDOI
TL;DR: In this paper, a 30-A-thick layer of intermixed platinum and silicon is identified at the metal-silicide interface when 50 A of Pt is electron beam evaporated onto room-temperature Si.
Abstract: The metallurgical interaction at the interface between single‐crystal silicon substrates and thin films of elemental platinum has been examined using the complementary techniques of high‐resolution cross‐sectional transmission electron microscopy (HRXTEM), Auger sputter profiling, and MeV ion channeling. We identify the existence of a 30‐A‐thick layer of intermixed platinum and silicon which forms at the metal‐silicide interface when 50 A of Pt is electron beam evaporated onto room‐temperature Si. The interfacial layer is evident in the HRXTEM as a uniform band of dark and noncrystalline contrast. In Auger sputter profiling, the evolution of the Si LVV line shape indicates the presence of a platinum silicide region adjacent to the film/Si interface but not at the surface of the Pt film. MeV ion channeling reveals that ∼1.5×1016 Si atoms/cm2 are displaced from their substrate lattice sites upon Pt deposition. In addition, the HRXTEM reveals islands of unreacted Pt and occasional grains of Pt2Si on top of t...

Journal ArticleDOI
TL;DR: In this paper, the local structure of coke is determined from the fine structure at the high energy side of the CK EELS peak, in comparison with reference compounds such as graphite, coronene, and pentacene.

Journal ArticleDOI
TL;DR: In this article, high quality La1.8Sr0.2CuO4 and YBa2Cu3O7 superconducting thin films, with zero resistance at 88 K, have been made by dual-ion-beam sputtering of metal and oxide targets at elevated temperatures.
Abstract: High quality La1.8Sr0.2CuO4 and YBa2Cu3O7 superconducting thin films, with zero resistance at 88 K, have been made by dual‐ion‐beam sputtering of metal and oxide targets at elevated temperatures. The films are about 1.0 μm thick and are single phase after annealing. The substrates investigated are Nd‐YAP, MgO, SrF2, Si, CaF2, ZrO2‐9% Y2O3, BaF2, Al2O3, and SrTiO3. Characterization of the films was carried out using Rutherford backscattering spectroscopy, resistivity measurements, transmission electron microscopy, x‐ray diffraction, and secondary ion mass spectroscopy. Substrate/film interaction was observed in every case. This generally involves diffusion of the substrate into the film, which is accompanied by, for example, the replacement of Ba by Sr in the YBa2Cu2O7 structure, in the case of SrTiO3 substrate. The best substrates were those that did not significantly diffuse into the film and which did not react chemically with the film. In general, the superconducting transition temperature is found to ...

Journal ArticleDOI
TL;DR: The formation process of barium hexaaluminate from BaCO3/γ-Al2O3 powders or hydrolyzed alkoxides was studied by analytical electron microscopy as mentioned in this paper.
Abstract: The formation process of barium hexaaluminate (BaO 6Al2O3) from BaCO3/γ-Al2O3 powders or hydrolyzed alkoxides was studied by analytical electron microscopy. Barium hexaaluminate is produced by a two-step solid-state reaction from BaCO3 and Al2O3 via formation of BaO·Al2O3. Marked grain growth and inclusion of nonequilibrium phase were inevitable in this powder mixture process. However, in an alkoxide-derived precursor, homogeneous mixing of components is attained and hence the formation of BaO·6Al2O3 proceeds readily. Powders obtained by this latter route consisted of fine planar particles with a uniform size and retained a large surface area (20.2 m2/g) even after heating at 1300°C. Electron diffraction results implied that suppression of crystal growth along the c axis is the reason for the large surface area of BaO·6Al2O3.

Journal ArticleDOI
TL;DR: In this article, the crystallization behavior of amorphous Ni-P electroless deposited coatings under two different time-temperature series conditions was investigated by using transmission electron microscopy.

Journal ArticleDOI
TL;DR: In this paper, the resonance propagation of the electron beam along the top few atomic layers of the surface in the RHEED geometry results in the excitation of surface states in MgO(100) and ensures sensitivity to the surface composition and structure.


Journal ArticleDOI
TL;DR: In this paper, a mixture of pure germanium films and Si(100) substrates was formed by pulsed laser induced mixing of pure Germanium film and Si substrates under 1×10−7 Torr vacuum.
Abstract: Heteroepitaxial GexSi1−x alloy layers have been formed by pulsed laser induced mixing of pure germanium films and Si (100) substrates. Ge films 50–200 A thick are electron beam evaporated onto Si (100) under ≤1×10−7 Torr vacuum. The near surface of the sample then undergoes a rapid melt and regrowth process using 2–10 pulses from a XeCl excimer laser. The laser has a 37‐ns pulse width at 308 nm and its energy density of 0.5–1.5 J/cm2 is precisely homogenized into a 4×4 mm square area. The alloy layers are 250–1600 A thick, have a Ge fraction x=2.5–19%, and exhibit excellent crystallinity as evaluated by MeV ion channeling and lattice resolution cross‐sectional transmission electron microscopy. Unlike layer growth by molecular beam epitaxy, this approach is insensitive to minor levels of contamination because the original Ge/Si interface is melted through during the laser processing.

Journal ArticleDOI
TL;DR: In this article, the initial reaction in amorphous Si-Ti-amorphous Si trilayers was investigated with Auger electron spectroscopy, transmission electron microscopy, and x-ray diffraction.
Abstract: The initial reaction in amorphous Si‐Ti‐amorphous Si trilayers was investigated with Auger electron spectroscopy, transmission electron microscopy, and x‐ray diffraction. It was clearly demonstrated that at temperatures not exceeding 450 °C an amorphous Ti‐Si alloy is formed. At temperatures of 500 °C and higher, crystalline TiSi2 with the ZrSi2 (C49) structure was found. The growth kinetics of the amorphous silicide could not be described by a simple diffusion controlled process. It was shown that at 400 °C the thickness of the amorphous silicide is limited to approximately 18 nm. Since it was found that the growth of the amorphous phase is accompanied by excessive Kirkendall void formation, it is proposed that these voids eventually suppress the growth of amorphous silicide. The composition of the amorphous phase was determined to be between TiSi0.9 and TiSi1.2, i.e., close to the composition of the monosilicide.

Journal ArticleDOI
TL;DR: In this paper, the initial growth process has been observed in situ by transmission electron microscopy (TEM), and it became clear that β-W clusters are formed by electron beam irradiation of the WF6 adlayer.
Abstract: W deposition, using a WF6 source and electron‐beam‐induced surface reaction, has been studied by transmission electron microscopy (TEM). The initial growth process has been observed in situ by TEM. As a result, it became clear that β‐W clusters are formed by electron beam irradiation of the WF6 adlayer. Moreover, it has been observed that W layers are formed by coalescing the W clusters by electron beam irradiation at 5×10−7 Torr WF6 gas pressure. Furthermore, a nanostructure involving a W rod with 15 nm diameter has been demonstrated by using electron‐beam‐induced surface reaction.

Journal ArticleDOI
TL;DR: In this article, it was shown that interface reactions in semiconductor materials can be recorded under high-resolution conditions in a large proportion of cases, and that events typical of the bulk can be observed under high resolution conditions.
Abstract: Progress in introducing high-resolution electron microscopy at controlled elevated temperatures is described. Initial work involved the study of dynamic events in materials like cadmium telluride which can be heated to a sufficient degree by the imaging beam. However, for reproducible experiments the temperature must be carefully controlled and measured, and this involves a heating specimen holder. Results achieved recently this way on a variety of substances including CdTe, GaAs, Si, GaAs-Ti, GaAs-Ni, Si- Mo and Si-Ti, are reported. To derive information pertinent to bulk behavior both the manner of an in situ reaction and its kinetics should be compared with those for specimens prepared from macroscopic materials treated ex situ. For interface reactions in semiconductor materials it is found that events typical of the bulk can be recorded under high-resolution conditions in a large proportion of cases.

Journal ArticleDOI
TL;DR: In this paper, the chemical stoichiometry and structure of 2-10nm-thick polycrystalline films have been characterized by Auger electron spectroscopy, transmission electron microscopy, electron diffractions, and direct-phase detection microscopic interferometry.
Abstract: The chemical stoichiometry and structure of 2-10-nm-thick Pt films deposited on molecularly smooth mica have been characterized by Auger electron spectroscopy, transmission electron microscopy, electron diffractions, and direct-phase-detection microscopic interferometry. These analyses are correlated with electrical, optical, and electrochemical properties of the films with regard to their used in surface forces microbalance techniques. Large-area (1 cm/sup 2/), 4-nm-thick polycrystalline films are sufficiently conductive (sigma > 10/sup 4/ ohm/sup -1/ cm/sup -1/) and transparent (55% T at lambda = 550 nm) to allow measurement of forces between metallic phases. Preliminary measurements of electrostatic forces between two Pt films separated by a thin layer of water are presented.

Journal ArticleDOI
TL;DR: In this article, the chemical composition and the crystal structure of the Bi-Ca-Sr-Cu-O oxide with a high Tc of about 75 K have been studied by the combined techniques of crystal structure imaging and spectroscopic microanalysis using a 400 kV high-resolution analytical electron microscope.
Abstract: The chemical composition and the crystal structure of the Bi-Ca-Sr-Cu-O oxide with a high-Tc of about 75 K have been studied by the combined techniques of crystal structure imaging and spectroscopic microanalysis using a 400 kV high-resolution analytical electron microscope. The crystal is orthorhombic with lattice parameters a=0.54 nm, b=2.70 nm and c=3.06 nm. The chemical composition is assigned as Bi2CaxSrzCu2Oy, where x and z are approximately 1.0 and 1.5, respectively. The structure image reveals that the structure is comprised of a bismuth oxide layer interleaved with an oxygen deficient perovskite-like layer. It is suggested that a nearly commensurate superstructure based on the perovskite-type structure is formed.

Journal ArticleDOI
TL;DR: The reconstructed structure of the Au(001)28×5 surface is observed by transmission electron microscopy and diffraction as discussed by the authors, where the hexagonal lattice of the reconstructed layer is contracted by ∼ 3.6% in the multifold and fivefold directions, respectively to form an incommensurate structure to the underlying square lattice.

Journal ArticleDOI
TL;DR: In this article, the carbon overcoats on commercial rigid disks with thin-film magnetic media are studied using transmission electron analysis (microscopy, microdiffraction, and energy-loss spectroscopy), Raman spectroglobalization, Auger spectroscopies, ellipsometry, x-ray diffraction and microhardness testing.
Abstract: Sputtered carbon overcoats on commercial rigid disks with thin‐film magnetic media are studied using transmission electron analysis (microscopy, microdiffraction, and energy‐loss spectroscopy), Raman spectroscopy, Auger spectroscopy, ellipsometry, x‐ray diffraction, and microhardness testing. Data from transmission electron analysis, Raman spectroscopy, and ellipsometry suggest that the carbon overcoats are composed of small graphite crystallites (≤2 nm), randomly oriented, with a small percentage (0%–5%) of fourfold coordinated carbon bonds. Auger spectroscopy and transmission electron energy‐loss spectroscopy indicate the presence of a small amount of oxygen. Auger spectroscopy also shows some surface nitrogen. The optical constants, n=2.1 and k=0.78, exhibit a small wavelength dependence. In addition, the extinction coefficient k shows a dependence upon film thickness. X‐ray diffraction and microhardness testing did not yield any information concerning the carbon overcoats. There was no indication of d...

Journal ArticleDOI
TL;DR: In this paper, high-resolution transmission electron microscopy and related diffraction techniques are applied to the characterization of argon implantation-induced amorphization of silicon at room temperature.
Abstract: Cross‐sectional high‐resolution transmission electron microscopy and related diffraction techniques are applied to the characterization of argon implantation‐induced amorphization of silicon at room temperature. Damage calculations have been performed to provide a theoretical support for the cross‐sectional transmission electron microscopy observations. It is shown that the amorphous‐crystalline interfacial roughness is strongly dependent on ion dose and hence on its depth location. The a‐c transition region was found to have sharply defined boundaries and sometimes exhibits defects such as dislocations and stacking‐fault nuclei. Combining the experimental measurement of the extension of the a layer for increasing dose, with concepts arising from the ‘‘critical damage energy density’’ model leads to a value of about 10 eV/atom for the c→a transformation. It is suggested that temperature effects are responsible for the observation that higher damage energy densities are apparently needed to produce a first continuous a layer than to extend this layer to greater depth.


Journal ArticleDOI
TL;DR: In this article, GaInP epitaxial crystals were examined by transmission electron microscopy, which revealed a lamellate-ordered domain structure of two variants of {111} superlattices, which was also investigated using cross-section and plan-view dark field electron micrographs.
Abstract: GaInP epitaxial crystals grown on (001) GaAs at 660–700 °C by metalorganic chemical vapor deposition are examined by transmission electron microscopy. The computer‐processed image of the high‐resolution electron micrograph clearly reveals a lamellate‐ordered domain structure of two variants of {111} superlattices, which is also investigated using cross‐section and plan‐view dark field electron micrographs. The spikes of well‐defined superspots in the diffraction pattern were found to originate from the shape of the domains. The investigation of GaInP grown with different Zn concentrations showed that the disordering occurs as a result of a decrease in the density rather than the size of the domain.

Journal ArticleDOI
TL;DR: The interaction of 40nm Pd layers on chemically cleaned (100) InP substrates has been examined in this paper where the samples were isochronally annealed in an Ar 5%H2 ambient at temperatures from 175 to 650°C.
Abstract: The interaction of 40‐nm Pd layers on chemically cleaned (100) InP substrates has been examined. The samples were isochronally annealed in an Ar‐5%H2 ambient at temperatures from 175 to 650 °C. Transmission electron microscopy, x‐ray diffraction, and Auger electron spectroscopy were used to study the phases that formed. The reaction began upon deposition. With subsequent annealing at 175 °C, an amorphous ternary phase of approximate composition Pd4.8InP0.7 was formed. For samples annealed at 215 and 250 °C, the tetragonal ternary phase, Pd5InP (a=0.3928 nm, c=0.6917 nm), was found. After higher‐temperature annealing (45–650 °C), the simple cubic phase PdIn (a=0.326 nm), was observed.