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1.
G. Kuri G. Materlik V. Hagen R. Wiesendanger 《Applied Physics A: Materials Science & Processing》2001,73(3):265-271
MgO (100) single crystals are implanted with 1.50-MeV Al+ and 3.00-MeV Al2
+ ions at a fluence of 1×1015 Al atoms cm-2 under high-vacuum conditions. The surface morphology of the substrate is measured in air using atomic force microscopy and
X-ray reflectometry followed by computer-simulated spectrum analysis. The ion-irradiated areas are found to protrude to different
heights on the nanometre scale. Small height differences are observed in the areas irradiated by Al+ and Al2
+ ions of comparable energy, dose rate and total fluence. The results indicate that protrusions are most likely caused by implantation-induced
point defects (vacancies) generated in the crystal during implantation. Other possibilities for the cause of protrusions are
discussed. Thermal treatment stimulates a partial recovery of the implantation damage and alters the topography of MgO surfaces.
Received: 22 May 2001 / Accepted: 30 May 2001 / Published online: 25 July 2001 相似文献
2.
G. Kuri 《Applied Physics A: Materials Science & Processing》1999,68(6):699-703
Analytical electron microscopy, high-resolution X-ray diffraction and combined Rutherford backscattering spectrometry and
channeling experiments have been used to investigate the radiation damage and the effect of post-implantation annealing on
the microstructure of GaAs(100) single crystals implanted with 1.00 MeV Cu+ ions to a dose of ≈ 3×1016 cm-2 at room temperature. The experiments reveal the formation of a thick and continuous amorphous layer in the as-implanted state.
Annealing up to 600 °C for 60 min does not result in the complete recovery of the lattice order. The residual disorder in
GaAs has been found to be mostly microtwins and stacking fault bundles. The redistribution of implanted atoms during annealing
results in the formation of nano-sized Cu particles in the GaAs matrix. The X-ray diffraction result shows a cube-on-cube
orientation of the Cu particles with the GaAs lattice. The depth distribution and size of the Cu particles have been determined
from the experimental data. A tentative explanation for these results is presented.
Received: 15 February 1999 / Accepted: 18 February 1999 / Published online: 28 April 1999 相似文献
3.
Motivated by ABR class of service in ATM networks, we study a continuous time queueing system with a feedback control of the
arrival rate of some of the sources. The feedback about the queue length or the total workload is provided at regular intervals
(variations on it, especially the traffic management specification TM 4.0, are also considered). The propagation delays can
be nonnegligible. For a general class of feedback algorithms, we obtain the stability of the system in the presence of one
or more bottleneck nodes in the virtual circuit. Our system is general enough that it can be useful to study feedback control
in other network protocols. We also obtain rates of convergence to the stationary distributions and finiteness of moments.
For the single botterneck case, we provide algorithms to compute the stationary distributions and the moments of the sojourn
times in different sets of states. We also show analytically (by showing continuity of stationary distributions and moments)
that for small propagation delays, we can provide feedback algorithms which have higher mean throughput, lower probability
of overflow and lower delay jitter than any open loop policy. Finally these results are supplemented by some computational
results.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
4.
Ayako Torikai Toshihiro Asai Toshio Suzuki Zen-Ichiro Kuri 《Journal of polymer science. Part A, Polymer chemistry》1975,13(4):797-805
ESR spectra and optical absorption spectra of γ-irradiated poly(methyl methacrylate) (PMMA) at 77°K and the photo- and thermal bleaching behavior have been studied. γ-Irradiation of PMMA yields a singles spectrum with a line width of 6 G which is bleachable with visible light. This species is assigned to the polymer cation. The unbleached species consists mainly of a four-line spectrum and is assigned to a polymer radical having a different CH2 conformation from the usual nine-line spectrum. On subsequent warming to room temperature, the spectrum changes into the nine-line spectrum. γ-Irradiation of PMMA containing biphenyl as an additive at 77°K gives biphenyl cation. Yield of polymer radical is reduced by the addition of biphenyl and 2-methyltetrahydrofuran. A mechanism is proposed which is consistent with the experimental results. 相似文献
5.
The variational principle based on an integral equation equivalent to the Schrödinger equation is employed to calculate energy levels ofDevonshire's model. 相似文献
6.
X-ray standing wave fields, excited in periodic nanostructured multilayers during Bragg diffraction, have been used to probe atomic migration in multilayers. Ion beam induced migration of Fe impurity atoms from the C layers to the Pt layers in a Pt(Fe)/C(Fe) multilayer, where each layer is about 2 nm thick, has been detected. With a depth resolution better than 0.2 nm of this technique, the direction of Fe migration (here outward) and the change of Fe concentration in C (also Pt) layers have been determined. The results of such measurements are important for understanding the properties of multilayers, for example, the evolution of ferromagnetism in the present example [Dev, Microelectron. Eng. 83, 1721 (2006)10.1016/j.mee.2006.01.230]. 相似文献
7.
This paper deals with the implantation of high-energy (1.0–3.0 MeV) atomic and molecular Al+ ions in Si(100) to a fluence of 5×1014 Al atoms/cm2 at room temperature. The molecular effect, i.e. the increase of the displacement yield compared with the sum of the atomic
yields, and the damage formation as well as defect behaviour after annealing have been investigated. A detailed experimental
study has been made of the evolution of extended secondary defects which form during thermal anneals of Al+ or Al2
+ irradiated silicon. The samples have been examined using combined Rutherford backscattering and channeling experiments together
with transmission electron microscopy observations. The surface structure of the implanted wafers has been measured by atomic
force microscopy. The results for the implantation-induced roughness at the Si surface, resulting from Al+ or Al2
+ irradiation at the same energy/atom, total atomic fluence, flux rate, and irradiation temperature, are presented and discussed.
Received: 19 August 1999 / Accepted: 20 October 1999 / Published online: 23 February 2000 相似文献
8.
9.
Secondary phase precipitates of a Zircaloy sample have been characterised by X-ray microspectroscopy. In Zircaloy-2 X-ray microscopy reveals pictures with a 40 nm resolution identifying Fe, Cr and to a lower occurrence Ni phases up to size of the micrometer. Analysis by X-ray spectroscopy defines the structure of specific secondary phase precipitates. The feasibility tests demonstrate that the characterisation of Fe and Cr can be performed on 100 nm size phases allowing the analysis of the Fe or Cr atoms environment in these secondary phase precipitates. 相似文献
10.
The purpose of this note is to give an extension of one of Jackson's theorems tomultivariables. 相似文献