The growth of crystals of the structurally related zeolites FAU and EMT may be characterized by layer upon layer propagation. This previously proposed mechanism has been confirmed by results of an investigation into the crystal growth features in zeolite Y by atomic force microscopy. The intergrowing surfaces of the crystal (see schematic representation on the right) are constructed by the deposition of sodalite‐like building units, leading to the formation of terraces.
We report on the current-voltage (IV) characteristics of GaAs/GaN/GaAs semiconductor-insulator-semiconductor structures as a function of temperature. IV measurements show a strong temperature dependence indicating a thermal distribution of carriers flowing over a barrier. From these data we deduce an effective conduction band barrier of 0.9 eV between GaAs and GaN.
Silicon nanoparticles were produced by a relatively low temperature (164 °C), solution-phase synthesis. The particles exhibit UV to blue photoluminescence (PL) which varied with excitation wavelength. The average lifetimes, excited at 300 nm, ranged from 4.4 to 5.9 ns. The mean particle diameter, determined by atomic force microscopy, was ≈1.08 nm. The PL spectra of particles passivated with methoxy or butyl groups were blue-shifted with respect to those passivated with hydroxy groups.
This letter presents an experimental study, using high-resolution atomic force microscopy, of the nature of the steps on the surface of GaInP layers lattice matched to GaAs substrates. The substrates were intentionally misoriented from the (001) plane by angles of 3°, 6°, and 9° toward [1̄10] and the layers were grown by organometallic vapor phase epitaxy at temperatures of 570, 620, and 720 °C. The surfaces consist of a mixture of monatomic (2.9 Å) [110] steps and [110] oriented supersteps with a distribution of heights from 2 to approximately 17 monolayers. The height of the largest steps increases monotonically with increasing misorientation angle. The supersteps are apparently formed by bunching of monatomic steps producing high index (11n) surfaces (n=4 to 7). This leaves relatively large (several hundred Å) (001) facets adjacent to the supersteps. The superstep height increases and the density decreases with increasing growth temperature. An attempt is made to correlate the supersteps to the degree of order and the microstructure of the ordered domains.
Longitudinal media for ultrahigh density recording require a high coercivity and a low medium noise. While the coercivity is controlled mainly by the chemical composition of the alloy, the medium noise is influenced significantly by the microstructure of the underlayer. We used atomic force microscopy (AFM) to study the microstructure of Cr underlayers and SmCo magnetic films. The AFM study shows that the Cr grains have elongated ‘‘rice’’-like granular features whereas the SmCo grains without an underlayer appear circular with nonuniform grain size. The Cr underlayer grows as well isolated columns with voids. When thin SmCo films (<20 nm) were deposited on the thin Cr (<35 nm) underlayers the SmCo grains were found to replicate the isolated, columnar structure of the underlayer. The intergranular exchange interaction and the recording media noise of SmCo/Cr thin films decreased with a decreasing thickness of the Cr underlayer. The medium noise of high coercivity SmCo/Cr hard disks prepared on thin Cr underlayers remained almost flat with no supralinear increase when tested up to 2760 fc/mm (70 kfci).
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