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Electron-beam-stimulated deposition and etching has been investigated as a clean, alternative method for nanoscale selective processing. Depositions using W(CO)6 and hydrocarbon sources have yielded efficient and selective electron-beam deposits. Primarily fluorine-based precursors have been used to etch a variety of materials. Initial results regarding the selective etching of silicon and silicon dioxide suggest that inelastic scattering of the primary electron beam with the gas occurs and is more severe at lower beam energies. The etch rate increases linearly with decreasing electron-beam energy, however, it is not clear if this is due to enhanced primary- or secondary-electron-stimulated processes. Feature sizes as small as 55 nm have been selectively processed.

Empirical forms have been found for the total and differential elastic scattering cross sections for electron/atom scattering. The cross sections are valid over the range 0.1–30 keV and across the periodic table. The empirical forms of the cross sections are derived from trends in tabulated Mott scattering cross sections. The form of the total cross section is similar to a previously published cross section and is based on the screened Rutherford cross section. The fit to the differential Mott cross sections is decomposed into two parts, one part being of the same mathematical form as the screened Rutherford cross section σR, and the second part being an isotropic distribution σI. These two mathematical forms were chosen because they give a straightforward generation of random scattering angles. The screened Rutherford part of the differential scattering cross section is first fitted to the half‐angle of the Mott cross sections. This fit of the differential screened Rutherford is in turn reduced to a fit ...

Single-wall carbon nanotubes (SWNT) were grown to micron lengths by laser-annealing nanoparticulate soot containing short (∼50 nm long) nanotube “seeds.” The “seeded” nanoparticulate soot was produced by restricting the time spent by an ablation plume inside an 800 °C oven following laser vaporization of a C–Ni–Co target. The soot collected from the laser vaporization apparatus was placed inside graphite crucibles under argon, and heated by a CO2 laser. In situ pyrometry was used to estimate the sample temperature. Length distributions of SWNT bundles in the unannealed and annealed samples were measured by transmission electron microscopy and field emission scanning electron microscopy. Annealing treatments exceeding 1600 °C produced no increase in nanotube length, while lower temperatures in the 1000–1300 °C range were optimal for growth. These experiments indicate that SWNT grow by the conversion of condensed phase nanomaterial during annealing, a similar mechanism to that proposed for growth during normal laser–vaporization production.

Calculations of Mott elastic scattering cross section of electrons for most elements of the periodic table up to element number 94 in the energy range 20 eV–20 keV have been performed. The Dirac equation transformed to a first‐order differential equation was solved numerically. The influence of the choice of atomic potential on the scattering factor was studied in comparison to a simple muffin‐tin approximation of the atomic potential in solids. The application of calculated cross sections to a conventional Monte Carlo model for electron scattering using modified Bethe equation is described and results concerning the electron backscattering for different atomic potentials are compared.

The monoatomic hydride layer on silicon was used as a prototype for resistless electron beam lithography. Arbitrary patterns with linewidths below 60 nm have been achieved. The variation of the linewidth with electron energy, electron dose, and substrate thickness was studied to determine the mechanisms that govern surface hydrogen desorption and subsequent pattern formation. Unlike in resist based lithography, no resolution enhancement was observed with decreasing substrate thickness. The experimental data in combination with Monte Carlo simulations of the backscattered and transmitted electrons suggest that surface hydrogen desorption and pattern formation are not strongly related to the backscattered electrons and the secondary electrons (energies

Electron holography performed in a transmission electron microscope, has been used to measure the width of 90° domain walls in tetragonal BaTiO3, and to determine the magnitude and distribution of the polarization across these walls. The walls are found to be between 15 and 25 A in width. The polarization and its measured variation are in good agreement with other estimates. Fringe splitting has been observed in some holograms and it is suggested that this is due to the presence of charged oxygen vacancies on the walls.

Carbon nanofibers are high-aspect ratio graphitic materials that have been investigated for numerous applications due to their unique physical properties such as high strength, low density, metallic conductivity, tunable morphology, chemical and environmental stabilities, as well as compatibility with organochemical modification. Surface studies are extremely important for nanomaterials because not only is the surface structurally and chemically quite different from the bulk, but its properties tend to dominate at the nanoscale due to the drastically increased surface-to-volume ratio. This review surveys recent developments in surface analysis techniques used to characterize the surface structure and chemistry of carbon nanofibers and related carbon materials. These techniques include scanning probe microscopy, infrared and electron spectroscopies, electron microscopy, ion spectrometry, temperature-programed desorption, and atom probe analysis. In addition, this article evaluates the methods used to modif...

With x‐ray diffraction techniques, it is possible to routinely measure lattice parameters to several parts in 104 for thin‐film samples. However, measurements of lattice parameter changes for quaternary device structures several microns in width are not usually feasible with x‐ray diffraction techniques. For this reason, transmission electron microscopy has been used to determine the position of higher‐order Laue zone lines within convergent‐beam electron diffraction patterns from thin foil cross sections of planar quaternary layers grown on InP substrates. A calibration curve has been generated which describes the position of higher‐order Laue zone lines as a function of the lattice parameter determined from x‐ray diffraction measurements. For the active quaternary region of an elecro‐optical device structure, it is shown that ths calibration procedure may be sensitive to a relative change in lattice parameter as small as ±2 parts in 104.

When a Si(Li) solid‐state energy dispersive detector is used to collect x‐ray photons with energies below 2 keV the characteristic peaks in the spectrum show significant deviations from the ideal Gaussian shape observed for higher energy photons. This effect is due to incomplete collection of the charge deposited by the incident photon in the diode. The magnitude of this effect, and the resultant distortion of the spectrum, can be computed by means of a Monte Carlo simulation which models the detector in terms of the three parameters which characterize it, junction depth, diffusion length, and surface recombination velocity. For values of these parameters typical of commercial detectors it is found that the incomplete charge correction can be as high as 30% for a line such as N Kα at 400 eV. By matching simulated and experimental spectral shapes, quantitative corrections for each x‐ray line of interest can be computed. The results suggest that alternative design strategies for detectors might permit a hig...

This article provides a comprehensive review of the theory, practice, and application of electron channeling patterns in the scanning electron microscope. An atlas of indexed channeling maps for the bcc, fcc, diamond cubic, and hcp systems is included with a bibliography of 240 references containing all known published work on electron channeling for crystallographic studies in the SEM.

Microstructural studies of Si‐Si interfaces grown by molecular beam epitaxy reveal pockets of oxygen‐rich material for certain substrate preparation conditions. For Czochralski substrates which are cleaned using an argon ion sputtering technique, a high density (about 1011/cm2) of oxygen‐rich pockets about 30 A in size is observed using cross‐sectional transmission electron microscopy and x‐ray microanalysis for short (less than about 15 s) sputtering times. For longer sputtering times, no significant defect density is observed. Post‐deposition thermal annealing causes a dramatic increase in the density of oxygen‐rich defects, and it is suggested that this is due to trapping of oxygen which has diffused from the bulk of the substrate wafer. For (100) interfaces, no significant dislocation activity is associated with the defects, even for densities up to 1012/cm2. On (111) interfaces, however, a large planar fault density is observed. Ramifications for silicon homoepitaxy are discussed.

Transparent, stable, electrically insulating, crystalline thin films of two aromatic organic dianhydrides, 3,4,9,10‐perylenetetracarboxylic dianhydride C24H8O6 and 1,4,5,8‐naphthalenetetracarboxylic dianhydride C14H4O6, were prepared by vapor deposition. On exposure to an electron beam dose of 0.05 C cm−2 the written areas of the films appeared visually blackened and were electrically conducting. This chemical transformation was found to be both dose and current density dependent. Fine lines with widths of 1000 A were prepared by electron exposure at just above writing threshold doses. The chemical and electrical properties of the materials formed upon e‐beam treatment were found to be notably different from those of the starting anhydrides and useful for semiconductor device fabrication.

Contrast from domain walls in materials with cubic magnetic anisotropy has been observed in scanning electron microscope (SEM) images. This contrast, which is visible in both the backscattered and absorbed current images, with normal electron beam incidence arises from the interaction of the convergent incident electron beam with the domains on either side of the wall.

Measurement of thermionic electron emission values for pointed LaB6 single‐crystal emitter cathodes has shown that 〈110〉 axial orientations yield emission values ten times higher than 〈100〉 orientations at 1545 °K. Minimum values were obtained for the 〈510〉 directions. These findings seem encouraging in achieving perhaps two orders of magnitude higher emission fluxes as compared to tungsten emitters.

We have applied the scanning electron microscopy (SEM) technique of Fathers et al. to a study of domain structure in metallic glasses of the form TM0.75P0.16X0.06Al0.03, where TM denotes Fe, Co, Ni, or an alloy of these and X denotes either B, C, or Si. The domain structure is dominated by the presence of a spatially nonuniform uniaxial anisotropy which is related to the flow processes induced by quenching the molten alloy. The existence of both a magnetostrictive and a directional ordering source of anisotropy is indicated.

Measurements have been made of the functional form of the energy‐differential cross sections for carbon, using transmission electron energy‐loss spectroscopy. It is shown that both the characteristic K edge and the background, prior to the K edge, can be represented accurately by functions of the form AE−r, where E is the energy loss and A and r are constants. The values of the exponent in this expression for the K edge have been compared with calculated values derived from a hydrogenic model and good agreement has been obtained.