共查询到20条相似文献,搜索用时 171 毫秒
1.
I. P. Chernov S. V. Ivanova M. Kh. Krening N. Koval’ V. V. Larionov A. M. Lider N. S. Pushilina E. N. Stepanova O. M. Stepanova Yu. P. Cherdantsev 《Technical Physics》2012,57(3):392-398
A pulsed action of an electron beam on a Zr-1% Nb zirconium alloy is studied. Alloy samples are irradiated by three 50-μs
pulses at an energy density of 15–25 J/cm2, a power of (3–6) × 104 W/cm2, a current density of 10–50 A/cm2, and an electron energy of 18 keV. This method of processing is found to modify the surface layer of the alloy without changing
the structure-phase state of its volume. This surface modification increases the hydrogen saturation resistance of the alloy. 相似文献
2.
V. V. Uglov N. T. Kvasov Yu. A. Petukhov R. S. Kudaktin N. N. Koval’ Yu. F. Ivanov A. D. Teresov V. M. Astashinskii A. M. Kuz’mitskii 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2012,6(2):296-302
Structural phase changes in a titanium-silicon system treated by low-energy high-current electron beams (HCEBs) and compression
plasma flows (CPFs) with the duration 100 μs and the energy density 12–15 J/cm2 are studied. Scanning electron microscopy, X-ray diffraction and electron microprobe analysis are used in this work. The
formation of a titanium-doped silicon layer 10–25 μm thick, titanium silicides (TiSi2 under HCEBs and Ti5Si3 under CPF treatment), silicon dendrites, and needle-like eutectics (typical size of precipitates is about 50 nm) is revealed.
It is shown via the results of numerical simulation that the thickness of the metal-doped layer is mainly controlled by the
power density value and the surface nonuniformity of the heat flow over the target surface. The thermodynamic regularities
of phase formation are discussed, taking into account heat transfer between the silicide nuclei and solid silicon. 相似文献
3.
V. V. Uglov N. T. Kvasov Yu. A. Petukhov V. M. Astashinskii A. M. Kuz’minskii 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2010,4(2):338-342
The results of the study of structural and phase transformations in the silicon substrate-chromium coating system exposed
to compression plasma fluxes with power densities of 0.3–1.2 GW/m2 are discussed. The formation of hexagonal chromium disilicide and an amorphous phase, the growth of silicon dendrites, and
the appearance of a chromium-enriched near-surface layer are revealed effects. The mechanisms of structural and phase transformations
caused by rapid cooling of a mixed melt and concentration overcooling during solidification are analyzed. 相似文献
4.
N. G. Galkin V. M. Astashynski E. A. Chusovitin K. N. Galkin T. A. Dergacheva A. M. Kuzmitski E. A. Kostyukevich 《Journal of Applied Spectroscopy》2009,76(6):840-846
Consecutive plasma-epitaxial synthesis on silicon wafers is used for the first time to fabricate monolithic nanoheterostructures
with embedded nanocrystals (NC) of chromium disilicide (Si–NC CrSi2–Si). It is found that, initially, nanoislands form on the surface and within a coating layer of silicon, followed by the
formation of small (10–15 nm) nanocrystals of semiconducting chromium disilicide (CrSi2) at a high occupation density ((2–3)⋅1011 cm–2). During formation of silicon-silicide-silicon heterostructures, CrSi2 nanocrystallites “float up” into the near surface area of the covering silicon layer. 相似文献
5.
Samples of single-crystal silicon implanted with iron-group ions are investigated by electron paramagnetic resonance (EPR).
The change in relative permittivity μr of the silicon layer modified by implanted nickel ions is found. The accumulation kinetics of paramagnetic centers of amorphous
regions of silicon implanted with Co, Ni, and Fe are shown to be different. Magnetic hysteresis for both the wide EPR line
due to implanted impurities and the EPR line due to dangling chemical silicon bonds is found.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 2, pp. 197–201, March–April, 2008. 相似文献
6.
T. Sameshima Y. Kaneko N. Andoh 《Applied Physics A: Materials Science & Processing》2001,73(4):419-423
50-nm thick amorphous silicon films formed on glass substrates were crystallized by rapid Joule heating induced by an electrical
current flowing in 100-nm-thick Cr strips formed adjacently to 200-nm-thick SiO2 intermediate layers. 3-μs-pulsed voltages were applied to the Cr strips. Melting of the Cr strips caused a high Joule heating
intensity of about 1×106 W/cm2. Raman scattering measurements revealed complete crystallization of the silicon films at a Joule heating energy of 1.9 J/cm2 via the SiO2 intermediate layer. Transmission electron microscopy measurements confirmed a crystalline grain size of 50–100 nm. 1-μm-long
crystalline grain growth was also observed just beneath the edge of the Cr strips. The electrical conductivity increased from
10-5 S/cm to 0.3 S/cm for 7×1017-cm-3-phosphorus-doped silicon films because of activation of the phosphorus atoms because of crystallization. The numerical analysis
showed a density of localized defect states at the mid gap of 8.0×1017 cm-3. Oxygen plasma treatment at 250 °C and 100 W for 5 min reduced the density of the defect states to 2.7×1017 cm-3.
Received: 3 April 2001 / Accepted: 9 April 2001 / Published online: 25 July 2001 相似文献
7.
V. N. Bagratashvili S. G. Dorofeev A. A. Ischenko V. V. Koltashev N. N. Kononov A. A. Krutikova A. O. Rybaltovskii G. V. Fetisov 《Russian Journal of Physical Chemistry B, Focus on Physics》2010,4(7):1164-1170
With the use of supercritical carbon dioxide (SC-CO2), the matrix immobilization of photoluminescent silicon nanocrystals (nc-Si) in polytetrafluoroethylene microparticles (mp-PTFE)
is performed, which leads to the formation of mp-PTFE/nc-Si photoluminescent nanocomposite containing ∼103–104 nc-Si particles per mp-PTFE particle (1–2 μm in size). This approach is based on the effect of polymer swelling in SC-CO2, efficient SC-CO2-assisted transport of nanoparticles into the internal free volume of the polymer, and contraction of the nanocomposite after
the release of CO2, an effect that prevents the subsequent agglutination of nanoparticles. Particles of nc-Si photoluminescent in the visible
spectrum were synthesized from silicon suboxide powder (SiO
x
, x ≈ 1) heated at various temperatures within 25–950°C and then etched in concentrated hydrofluoric acid. The hydrosilylation
procedure was used to graft 1-octadecene molecules to the surface of nc-Si particles. As a result, the photoluminescence intensity
of nc-Si increased substantially. According to TEM images and small angle X-ray scattering data, the maximum size of nc-Si
particles did not exceed 5 nm and 7 nm, respectively, and the core of these nanoparticles consisted of crystalline silicon.
The structure and spectral properties of the initial nc-Si particles and synthesized mp-PTFE/nc-Si photoluminescent nanocomposite
microparticles were studied. 相似文献
8.
D. Golberg P.S. Dorozhkin Y. Bando Z.-C. Dong C.C. Tang Y. Uemura N. Grobert M. Reyes-Reyes H. Terrones M. Terrones 《Applied Physics A: Materials Science & Processing》2003,76(4):499-507
Transport and field-emission properties of as-synthesized CNx and BNCx (x<0.1) multi-walled nanotubes were compared in detail. Individual ropes made of these nanotubes and macrofilms of those
were tested. Before measurements, the nanotubes were thoroughly characterized using high-resolution and energy-filtered electron
microscopy, electron diffraction and electron-energy-loss spectroscopy. Individual ropes composed of dozens of CNx nanotubes displayed well-defined metallic behavior and low resistivities of ∼10–100 kΩ or less at room temperature, whereas
those made of BNCx nanotubes exhibited semiconducting properties and high resistivities of ∼50–300 MΩ. Both types of ropes revealed good field-emission
properties with emitting currents per rope reaching ∼4 μA(CNx) and ∼2 μA (BNCx), albeit the latter ropes se- verely deteriorated during the field emission. Macrofilms made of randomly oriented CNx or BNCx nanotubes displayed low and similar turn-on fields of ∼2–3 V/μm. 3 mA/cm2 (BNCx) and 5.5 mA/cm2 (CNx) current densities were reached at 5.5 V/μm macroscopic fields. At a current density of 0.2–0.4 mA/cm2 both types of compound nanotubes exhibited equally good emission stability over tens of minutes; by contrast, on increasing
the current density to 0.2–0.4 A/cm2, only CNx films continued to emit steadily, while the field emission from BNCx nanotube films was prone to fast degradation within several tens of seconds, likely due to arcing and/or resistive heating.
Received: 29 October 2002 / Accepted: 1 November 2002 / Published online: 10 March 2003
RID="*"
ID="*"Corresponding author. Fax: +81-298/51-6280, E-mail: golberg.dmitri@nims.go.jp 相似文献
9.
C. Lazzaroni P. Chabert A. Rousseau N. Sadeghi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,60(3):555-563
A microplasma is generated in the microhole (400 μm diameter) of a
molybdenum-alumina-molybdenum sandwich (MHCD type) at medium pressure
(30–200 Torr) in pure argon. Imaging and emission spectroscopy have been
used to study the sheath and electron density dynamics during the stationary
normal regime and the self-pulsing regime. Firstly, the evolution of the
microdischarge structure is studied by recording the emission intensity of
the Ar (5p[3/2]1–4s[3/2]1)_{1}) line at 427.217 nm, and Ar+
(4p′
2P3/2–4s′
2D5/2)_{5/2}) line at 427.752 nm. The maximum of
the Ar+ line is located in the vicinity of the sheath-plasma edge. In
both regimes, the experimental observations are consistent with the position
of the sheath edge calculated with an ionizing sheath model. Secondly, the
electron density is recorded by monitoring the Stark broadening of the
Hb_\beta-line. In the self-pulsing regime at 150 Torr, the electron
density reaches its maximum value of 4 × 1015 cm-3, a few
tens of ns later than the discharge current maximum. The electron density
then decays with a characteristic decay time of about 2 μs, while the
discharge current vanishes twice faster. The electron density in the
steady-state regime is two orders of magnitude lower, at about 6–8 ×
1013 cm-3. 相似文献
10.
+ -Si/Ti/WNx/Al multi-layer metallization scheme. The contact resistance has been strongly related to the plasma nitridation of the Ti
surface because the contact resistance of n+-Si/Ti/WNx/Al with contact size of 0.49 μm2 about 100–130 Ω, whereas without the nitridation of the Ti surface the contact resistance rises up to 200–390 Ω. 19F (p,αγ) nuclear resonance analysis and Auger electron spectroscopy reveal that F adatoms on the Ti surface are successfully
removed by the 30 s nitridation and as a result, the low contact resistance can be achieved.
Received: 16 July 1996/Accepted: 5 November 1996 相似文献
11.
N+BF<Subscript>2</Subscript> and N+C+BF<Subscript>2</Subscript> high-dose co-implantation in silicon
L. Barbadillo M. Cervera M.J. Hernández P. Rodríguez J. Piqueras S.I. Molina A. Ponce F.M. Morales 《Applied Physics A: Materials Science & Processing》2003,76(5):791-800
Nitrogen and boron BF2, and nitrogen, carbon, and boron BF2 high-dose (6×1016–3×1017 cm-2) co-implantation were performed at energies of about 21–77 keV. Subsequent high-temperature annealing processes (600, 850,
and 1200 °C) lead to the formation of three and two surface layers respectively. The outer layer mainly consists of polycrystalline
silicon and some amorphous material and Si3N4 inclusions. The inner layer is highly defective crystalline silicon, with some inclusions of Si3N4 too. In the N+B-implanted sample the intermediate layer is amorphous. Co-implantation of boron with nitrogen and with nitrogen
and carbon prevents the excessive diffusivity of B and leads to a lattice-parameter reduction of 0.7–1.0%.
Received: 10 January 2002 / Accepted: 30 May 2002 / Published online: 4 November 2002
RID="*"
ID="*"Corresponding author. Fax: +34-91/3974895; E-mail: Lucia.Barbadillo@uam.es 相似文献
12.
Sonja Hermann Nils-Peter Harder Rolf Brendel Dirk Herzog Heinz Haferkamp 《Applied Physics A: Materials Science & Processing》2010,99(1):151-158
In this work, we report on laser ablation of thermally grown SiO2 layers from silicon wafer substrates, employing an 8–9 ps laser, at 1064 (IR), 532 (VIS) and 355 nm (UV) wavelengths. High-intensity
short-pulse laser radiation allows direct absorption in materials with bandgaps higher than the photon energy. However, our
experiments show that in the intensity range of our laser pulses (peak intensities of <2×1012 W/cm2) the removal of the SiO2 layer from silicon wafers does not occur by direct absorption in the SiO2 layer. Instead, we find that the layer is removed by a “lift off” mechanism, actuated by the melting and vaporisation of
the absorbing silicon substrate. Furthermore, we find that exceeding the Si melting threshold is not sufficient to remove
the SiO2 layer. A second threshold exists for breaking of the layer caused by sufficient vapour pressure. For SiO2 layer ablation, we determine layer thickness dependent minimum fluences of 0.7–1.2 J/cm2 for IR, 0.1–0.35 J/cm2 for VIS and 0.2–0.4 J/cm2 for UV wavelength. After correcting the fluences by the reflected laser power, we show that, in contrast to the melting threshold,
the threshold for breaking the layer depends on the SiO2 thickness. 相似文献
13.
Bi2S3 nanotubes and de-doped poly(3,4-ethylenedioxythiophene) (PEDOT) composite nanopowders were synchronously synthesized by a
one-pot self-assembly method. The powders were characterized by X-ray powder diffraction, infrared spectroscopy, and transmission
electron microscopy, respectively. Thermoelectric properties of the Bi2S3–PEDOT composite nanopowders with different Bi2S3 contents after being cold pressed into pellets were measured at room temperature. The sample with 36.1 wt% Bi2S3 has a highest power factor of 2.3 μWm−1K−2, which is higher than that of both pure PEDOT (0.445 μWm−1K−2) and Bi2S3 (1.94 μWm−1K−2). 相似文献
14.
A. I. Yenzhyieuski M. V. Bogdanovich G. I. Ryabtsev V. V. Suprun A. V. Grigor’ev A. G. Ryabtsev M. A. Shchemelev 《Journal of Applied Spectroscopy》2009,76(4):476-481
Judd–Ofelt parameters (Ω2 = 5.09∙10–20, Ω4 = 0.92∙10–20, and Ω6 = 0.63∙10–20 cm2) and oscillator strengths of fundamental optical transitions involved in lasing at wavelength 1.54 μm have been calculated
for borosilicophosphate glass co-activated with Er3+ and Tb3+ ions based on experimental luminescence and absorption spectra and refractive indices. The results were used to determine
the emission (6∙10–23 cm2) and absorption (5∙10–21 cm2) cross sections for λ = 1.54 μm and the gain cross section as a function of inverse population levels. 相似文献
15.
Pogorelsky I. V. Polyanskiy M. N. Babzien M. Yakimenko V. Dover N. P. Palmer C. A. J. Najmudin Z. Schreiber J. Shkolnikov P. Dudnikova G. 《Laser Physics》2011,21(7):1288-1294
A picosecond CO2 laser was used successfully in a number of experiments exploring advanced methods of particle acceleration [1]. Proton acceleration
from gas-jet plasma exemplifies another advantage of employing the increase in laser wavelength from the optical to the mid-IR
region. Recent theoretical- and experimental-studies of ion acceleration from laser-generated plasma point to better ways
to control the ion beam’s energy when plasma approaches the critical density. Studying this regime with solid-state lasers
is problematic due to the dearth of plasma sources at the critical electron density ∼1021 cm−3, corresponding to laser wavelength λ = 1 μm. CO2 laser offers a solution. The CO2 laser’s 10 μm wavelength shifts the critical plasma density to 1019 cm−3, a value attainable with gas jets. Capitalizing on this approach, we focused a circular polarized 1-TW CO2 laser beam onto a hydrogen gas jet and observed a monoenergetic proton beam in the 1–2 MeV range. Simultaneously, we optically
probed the laser/plasma interaction region with visible light, revealing holes bored by radiation pressure, as well as quasi-stationary
soliton-like plasma formations. Our findings from 2D PIC simulations agree with experimental results and aid in their interpretation. 相似文献
16.
V. P. Rotshtein Yu. F. Ivanov A. B. Markov D. I. Proskurovskii K. V. Oskomov V. V. Uglov S. N. Dub Y. Pauleau I. A. Shulepov 《Russian Physics Journal》2005,48(12):1221-1228
The surface topography, chemical composition, microstructure, nanohardness, and tribological characteristics of a Cu (film,
512 nm)-stainless steel 316 (substrate) system subjected to pulsed melting by a low-energy (20–30 keV), high-current electron
beam (2–3 μs, 2–10 J/cm2) were investigated. The film was deposited by sputtering a Cu target in the plasma of a microwave discharge in argon. To
prevent local exfoliation of the film due to cratering, the substrate was multiply pre-irradiated with 8–10 J/cm2. On single irradiation, the bulk of the film survived, and a diffusion layer containing the film and substrate components
was formed at the interface. The thickness of this layer was 120–170 nm irrespective of the energy density. The diffusion
layer consisted of subgrains of γ-Fe solid solution and nanosized particles of copper. In the surface layer of thickness 0.5–1 μm, which included the copper
film quenched from melt and the diffusion layer, the nanohardness and the wear resistance nonmonotonicly varied with energy
density, reaching, respectively, a maximum and a minimum in the range 4.3–6.3 J/cm2. As the number of pulsed melting cycles was increased to five in the same energy density range, there occurred mixing of
the film-substrate system and a surface layer of thickness ∼2 μm was formed which contained ∼20 at. % copper. Displacement
of the excess copper during crystallization resulted in the formation of two-phase nanocrystal interlayers separating the
γ-phase grains.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 6–13, December, 2005. 相似文献
17.
V. E. Fortov A. P. Nefedov V. M. Torchinskii V. I. Molotkov A. G. Khrapak O. F. Petrov K. F. Volykhin 《JETP Letters》1996,64(2):92-98
The formation of macroscopic ordered structures in the standing striations of a stationary glow discharge in Ne is observed.
A Coulomb quasicrystal is formed by spherical glass particles with diameters of 50–63 μm and charge Z
p~7·105
e. The interparticle distance is approximately 300 μm. This corresponds to a nonideality parameter Γ~5·104, which leads to crystallization in the Yukawa model. The factors leading to the formation of a quasicrystal in the striations
are discussed.
Pis’ma Zh. éksp. Teor. Fiz. 64, No. 2, 86–91 (25 July 1996) 相似文献
18.
Y. Isshiki J. Shi H. Nakai M. Hashimoto 《Applied Physics A: Materials Science & Processing》2000,70(4):395-402
Laser surface alloying (LSA) with silicon was conducted on austenitic stainless steel 304. Silicon slurry composed of silicon
particle of 5 μm in average diameter was made and a uniform layer was supplied on the substrate stainless steel. The surface
was melted with beam-oscillated carbon dioxide laser and then LSA layers of 0.4–1.2 mm in thickness were obtained. When an
impinged energy density was adjusted to be equal to or lower than 100 W mm−2, LSA layers retained rapidly solidified microstructure with dispersed cracks. In these samples, Fe3Si was detected and the concentration of Si in LSA layer was estimated to be 10.5 wt.% maximum. When the energy density was
equal to or greater than 147 W mm−2, cellular grained structure with no crack was formed. No iron silicate was observed and alpha iron content in LSA layers
increased. Si concentration within LSA layers was estimated to be 5 to 9 wt.% on average. Crack-free as-deposited samples
exhibited no distinct corrosion resistance. The segregation of Si was confirmed along the grain boundaries and inside the
grains. The microstructure of these samples changed with solution-annealing and the corrosion resistance was fairly improved
with the time period of solution-annealing.
Received: 2 September 1999 / Accepted: 6 September 1999 / Published online: 1 March 2000 相似文献
19.
Experimental performance parameters of Hg implanted Hg1−x
Cd
x
Te photovoltaic detectors are analyzed. At 77K, for 8–14 μm band, a comparison is made between performances and theoretical
ultimate diffusion limits in low frequency direct detection. Experimental features are well-explained by a model based on
the Auger band-to-band process for carrier recombination. Peak detectivities exceeding 1011 cm Hz1/2W−1, external quantum efficiencies as high as 90%, and zero-bias resistance-area products better than 1 Ω·cm2 have been achieved in devices with 12 μm cutoff wavelengths. In the 3–5 μm band performances are far from the diffusion limit.
Notwithstanding, at 77K zero-bias resistance-area products are better than 104Ω·cm2 and detectivities of the order of 1012 cm Hz1/2W−1 were observed at 5 μm.
Predominant generation-recombination contribution are present at room temperature in 1–1.3 μm photodiodes whose detectivities,
primarily limited by the Johnson noise, at 1.3 μm are higher than 1011 cm Hz1/2W−1 at 300 K.
The high frequency response of the photodiodes is also discussed. Response times as low as 0.5 ns are reached despite some
limitations arising from the implanted layer sheet resistance.
Work supported by CNR-CISE contract No. 73.01435. 相似文献
20.
T. A. Alekhova V. Ya. Shklover N. A. Zagustina N. V. Shvyndina A. D. Plotnikov A. L. Vasil’ev 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2010,4(5):747-753
The surfaces of AMg6 (aluminum-magnesium) alloy samples that have passed accelerated biocorrosion tests have been investigated
in a Quanta-3D scanning electron microscope. The alloy samples have been treated with the Ulocladium botrytis Preuss fungus, which is an active destructive fungus and was previously extracted on surfaces of the International Space Station.
Biocorrosion pits 2–10 μm in diameter, cavities the depths of which can reach 70–250 μm depth, and spots of modified color
are found to be the most typical defects. The surfaces of large cavities consist of faceted cubic particles that are formed
when the acid products of fungus metabolism interact with the alloy surface. The particles have an average size of 30 μm,
which is close to the size of alloy grains. The microstructure of a biocorrosion layer has been investigated in a Quanta-3D
microscope with the use of a focused Ga+ ion beam. The samples of 12-μm-wide transverse slices are obtained near large cavities and investigated in a Tecnai G230ST transmission electron microscope. The X-ray microanalysis of the defective layer has revealed the high concentration of
oxygen in this layer. Obtained images indicate that the corrosion cavity surface has a complex porous structure. 相似文献