共查询到20条相似文献,搜索用时 31 毫秒
1.
Lizhu Tong 《Central European Journal of Physics》2012,10(4):888-897
The effect of gas flow in low pressure inductively coupled Ar/N2 plasmas operating at the rf frequency of 13.56 MHz and the total gas pressure of 20 mTorr is studied at the gas flows of 5–700 sccm by coupling the plasma simulation with the calculation of flow dynamics. The gas temperature is 300 K and input power is 300 W. The Ar fractions are varied from 0% to 95%. The species taken into account include electrons, Ar atoms and their excited levels, N2 molecules and their seven different excited levels, N atoms, and Ar+, N+, N2 +, N4 + ions. 51 chemical reactions are considered. It is found that the electron densities increase and electron temperatures decrease with a rise in gas flow rate for the different Ar fractions. The densities of all the plasma species for the different Ar fractions and gas flow rates are obtained. The collisional power losses in plasma discharges are presented and the effect of gas flow is investigated. 相似文献
2.
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
3.
H. Martínez F. B. Yousif 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(3):493-498
This paper considers the electrical and optical characterization of glow
discharge pulsed plasma in N2/H2 gas mixtures at a pressures range
between 0.5 and 4.0 Torr and discharge current between 0.2 and 0.6 A.
Electron temperature and ion density measurements were performed employing a
double Langmuir probe. They were found to increase rapidly as the H2
percentage in the mixture was increased up to 20%. This increase slows
down as the H2 percentage in the gas mixture was increased above 20%
at the same pressure. Emission spectroscopy was employed to observe emission from the pulsed
plasma of a steady-state electric discharge. The discharge mainly emits
within the range 280–500 nm. The emission consists of N2 (C-X) 316, 336,
358 nm narrow peaks and a broad band with a maximum at λmax = 427 nm. Also lines of N2, N2
+ and NH excited states were
observed. All lines and bands have their maximum intensity at the discharge
current of 0.417 A. The intensities of the main bands and spectral lines are
determined as functions of the total pressure and discharge current.
Agreement with other theoretical and experimental groups was established. 相似文献
4.
O. Silvestre M.C. Pujol M. Rico F. Güell M. Aguiló F. Díaz 《Applied physics. B, Lasers and optics》2007,87(4):707-716
This paper presents the crystal growth and optical characterization of thulium-doped KLu(WO4)2 (KLuW). Thulium-doped KLuW macrodefect-free monoclinic single crystals (a*×b×c≈10×7×15 mm3) were grown by the top seeded solution growth slow cooling method with dopant concentrations of 0.5%, 1%, 3% and 5% atomic
in solution. The evolution of unit cell parameters in relation with thulium doping was studied by X-ray powder patterns. Thulium
energy levels in the KLuW host were determined by 6 K polarized optical absorption. The Judd–Ofelt parameters determined were
Ω2=9.01×10-20 cm2, Ω4=1.36×10-20 cm2 and Ω6=1.43×10-20 cm2. The maximum emission cross section for the 1.9 μm emission, calculated by Füchtbauer–Ladenburg method, is 1.75×10-20 cm2, at 1845 nm with E//Nm. The intensity decay time from the emitting levels 1
G
4 and 3
H
4 levels in relation to the concentration were studied. For the lowest thulium concentration, the measured decay times from
1
G
4 and 3
H
4 emitting levels are 140 μs and 230 μs, respectively.
PACS 42.55.Rz; 78.20.-e; 78.55.-m 相似文献
5.
H. Cherkani-Hassani D. S. Belic J. J. Jureta J. Lecointre P. Defrance 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,58(1):85-94
Absolute cross-sections for electron-impact dissociative ionization of C2
H2+ and C2 D2+ to CH+, C+, C2+ , H+, CH2+
and C2D+ fragments are determined for electron energies ranging
from the corresponding threshold to 2.5 keV. Results obtained in a crossed
beams experiment are analyzed to estimate the contribution of dissociative
ionization to each fragment formation. The dissociative ionization cross
sections are seen to decrease for more than an order of magnitude, from
CH+ (5.37±0.10) × 10-17 cm2 over C+ (4.19±
0.16) × 10-17 cm2, C2D+ (3.94±0.38) ×
10-17 cm2, C2+ (3.82±0.15) × 10-17 cm2
and H+ (3.37±0.21) × 10-17 cm2 to CH2+
(2.66±0.14) × 10-18 cm2. Kinetic energy release
distributions of fragment ions are also determined from the analysis of the
product velocity distribution. Cross section values, threshold energies and
kinetic energies are compared with the data available from the literature.
Conforming to the scheme used in the study of the dissociative excitation of
C2H2+
( C2 D2+ )\left( {\rm C}_2 {\rm D}_2^+ \right), the cross-sections are presented in
a format suitable for their implementation in plasma simulation codes. 相似文献
6.
Jose Antonio Ayllon Monica Lira-Cantu 《Applied Physics A: Materials Science & Processing》2009,95(1):249-255
The effects of oxygen content in the sputtering gas on the crystallographic and optoelectronic properties of 210 nm-thick
Zr–doped In2O3 (Zr–In2O3) films by rf magnetron sputtering were initially studied. The results of X-ray diffraction show that the Zr–In2O3 films grown on glass substrates exhibit mixed crystallographic orientations. Moreover, the Zr–In2O3 film grown in an Ar atmosphere promotes the appearance of crystallographic orientation of (222). The surface of the Zr–In2O3 film becomes rougher as the oxygen content in the sputtering gas decreases; the current images obtained by conductive atomic
force microscopy reveal that the surfaces of the Zr–In2O3 films exhibit a distribution of coexisting conducting and nonconducting regions, and that the area of the nonconducting surface
increases with the oxygen content in the sputtering gas. The resistivity is minimized to 3.51×10−4 Ω cm when the Zr–In2O3 film is grown in an Ar atmosphere and the average transmittance in the visible light region is ∼85%. The optical band gap
decreases as the oxygen content in the sputtering gas increases. 相似文献
7.
H. Cherkani-Hassani S. Cherkani-Hassani D. S. Belic J. J. Jureta J. Lecointre P. Defrance 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,58(1):75-83
Absolute cross-sections for electron-impact ionization and dissociation of
C2H2+ and C2D2+ have been measured for electron energies
ranging from the corresponding thresholds up to 2.5 keV. The animated
crossed beams experiment has been used. Light as well as heavy fragment ions
that are produced from the ionization and the dissociation of the target
have been detected for the first time. The maximum of the cross-section for
single ionization is found to be (5.56 ± 0.03)× 10-17 cm2 around 140 eV. Cross-sections for dissociation of C2
H2+ (C2D2+) to ionic products are seen to decrease for two orders
of magnitude, from C2D+ (12.6 ± 0.3) × 10-17 cm2 over CH+(9.55 ± 0.06) × 10-17 cm2,
C+ (6.66 ± 0.05) × 10-17 cm2, C2+ (5.36 ± 0.27) × 10-17 cm2, H+ (4.73 ±
0.29) × 10-17 cm2 and CH2+ (4.56 ± 0.27) × 10-18 cm2 to H2+ (5.68 ± 0.49) ×
10-19 cm2. Absolute
cross-sections and threshold energies have been compared with the scarce
data available in the literature. 相似文献
8.
Xinghua Zheng Lin Qiu Guoping Su Dawei Tang Yuchao Liao Yunfa Chen 《Journal of nanoparticle research》2011,13(12):6887-6893
A 3ω approach for the simultaneous determination of the effective thermal conductivity and thermal diffusivity of nanopowder
materials was developed. A 3ω experimental system was established, and the thermal properties of water and alcohol were measured
to validate and estimate the accuracy of the current experimental system. The effective thermal conductivity and thermal diffusivity
of the SiO2 nanopowder with 375, 475, and 575 nm diameters were measured at 290–490 K and at different densities. At room temperature,
the effective thermal conductivity and thermal diffusivity of the SiO2 nanopowder increased with temperature; however, both values decreased as the particle diameter was reduced. An optimum SiO2 powder density that decreased with decreasing diameter was also observed within the measurement range. The minimum effective
thermal conductivity and maximum effective thermal diffusivity were obtained at 85 × 10−3 kg/L, when the particle diameter was 575 nm. The optimum densities of the particles with 375 and 475 nm diameters were less
than 50.23 × 10−3 and 64.82 × 10−3 kg/L, respectively. 相似文献
9.
The absorption spectra, fluorescence spectrum and fluorescence decay curve of Nd3+ ions in CaNb2O6 crystal were measured at room temperature. The peak absorption cross section was calculated to be 6.202×10−20 cm2 with a broad FWHM of 7 nm at 808 nm for E//a light polarization. The spectroscopic parameters of Nd3+ ions in CaNb2O6 crystal have been investigated based on Judd-Ofelt theory. The parameters of the line strengths Ω
t
are Ω
2=5.321×10−20 cm2,Ω
4=1.734×10−20 cm2,Ω
6=2.889×10−20 cm2. The radiative lifetime, the fluorescence lifetime and the quantum efficiency are 167 μs, 152 μs and 91%, respectively. The fluorescence branch ratios are calculated to be β
1=36.03%,β
2=52.29%,β
3=11.15%,β
4=0.533%. The emission cross section at 1062 nm is 9.87×10−20 cm2. 相似文献
10.
S. Vatnik M. C. Pujol J. J. Carvajal X. Mateos M. Aguiló F. Díaz V. Petrov 《Applied physics. B, Lasers and optics》2009,95(4):653-656
The three thermo-optic coefficients of the biaxial laser host KLu(WO4)2 are measured at 633 nm by a deflection method. Their values at 300 K amount to ∂
n
g
/∂
T=−7.4×10−6 K−1; ∂
n
m
/∂
T=−1.6×10−6 K−1 and ∂
n
p
/∂
T=−10.8×10−6 K−1. Nearly athermal propagation directions are found for polarizations along the N
m
and N
p
dielectric axes. 相似文献
11.
V. P.S. Awana A. Vajpayee M. Mudgel V. Ganesan A. M. Awasthi G. L. Bhalla H. Kishan 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,62(3):281-294
We report synthesis, structure/micro-structure, resistivity under magnetic
field [ρ(T)H], Raman spectra, thermoelectric power S(T), thermal conductivity
κ(T), and magnetization of ambient pressure argon annealed
polycrystalline bulk samples of MgB2, processed under identical
conditions. The compound crystallizes in hexagonal structure with space
group P6/mmm. Transmission electron microscopy (TEM) reveals electron micrographs
showing various types of defect features along with the presence of 3–4 nm
thick amorphous layers forming the grain boundaries of otherwise crystalline
MgB2. Raman spectra of the compound at room temperature exhibited
characteristic phonon peak at 600 cm-1. Superconductivity is observed
at 37.2 K by magnetic susceptibility χ(T), resistivity ρ(T), thermoelectric power
S(T), and thermal conductivity κ(T) measurements. The power law fitting
of ρ(T) give rise to Debye temperature (ΘD) at 1400 K which is
found consistent with the theoretical fitting of S(T), exhibiting Θ
D of 1410 K and carrier density of 3.81 × 1028/m3. Thermal
conductivity κ(T) shows a jump at 38 K, i.e., at Tc, which was
missing in some earlier reports. Critical current density (Jc) of up to
105 A/cm2 in 1–2 T (Tesla) fields at temperatures (T) of up to 10 K
is seen from magnetization measurements. The irreversibility field, defined
as the field related to merging of M(H) loops is found to be 78, 68 and 42 kOe
at 4, 10 and 20 K respectively. The superconducting performance parameters
viz. irreversibility field (Hirr) and critical current density
Jc(H) of the studied MgB2 are improved profoundly with addition of
nano-SiC and nano-diamond. The physical property parameters measured for
polycrystalline MgB2 are compared with earlier reports and a
consolidated insight of various physical properties is presented. 相似文献
12.
Bi2Sr2CaCu2O8 thin films 200 nm thick were irradiated with 120 keV trivalent boron ions with the dose ranging from 1011 to 1014 ion/cm2. The critical parameters of the samples prior and after irradiation were monitored by non-resonance modulated microwave absorption
and Hall-probe techniques. For low doses of 1011–1012 ion/cm2, a slight increase in the critical current density and expansion of the area of the non-dissipative transport current flow
were revealed. Such results are explained by the formation of separate areas of displaced atoms, which serve as effective
pinning centers. The positive effects of irradiation faded away with dose increase of up to 1013–1014 ion/cm2. This is due to overlap of radiation-induced defects and weak pinning on them. 相似文献
13.
Single crystals of gadolinium orthosilicate Gd2SiO5 containing 0.5 at% and 5 at% of Sm3+ were grown by the Czochralski method. Optical absorption spectra, luminescence spectra and luminescence decay curves were
recorded for these systems at 10 K and at room temperature. Comparison of optical spectra recorded in polarized light revealed
that the anisotropy of this optically biaxial host affects the intensity distribution within absorption and emission bands
related to transitions between multiplets rather than the overall band intensity. It has been found that among four bands
of luminescence related to the 4G5/2→6HJ (J=5/2–11/2) transitions of Sm3+ in the visible and near infrared region the 4G5/2 →6H7/2 one has the highest intensity with a peak emission cross section of 3.54×10−21 cm2 at 601 nm for light polarized parallel to the crystallographic axis c of the crystal. The luminescence decay curve recorded
for Gd2SiO5:0.5 at% Sm3+ follows a single exponential time dependence with a lifetime 1.74 ms, in good agreement with the 4G5/2 radiative lifetime τ
rad=1.78 ms calculated in the framework of Judd-Ofelt theory. Considerably faster and non-exponential luminescence decay recorded
for Gd2SiO5:5 at% Sm3+ sample was fitted to that predicted by the Inokuti-Hirayama theory yielding the microparameter of Sm3+–Sm3+ energy transfer C
da=1.264×10−52 cm6×s−1. 相似文献
14.
The effect of gamma irradiation on the dielectric properties and ac conductivity of a TlInS2 single crystal with a layered structure has been investigated in the frequency range from 5 × 104 to 3.5 × 107Hz. It has been shown that gamma irradiation of the TlInS2 single crystal with a dose of 104–2.25 × 106 rad leads to a considerable increase in the dielectric loss tangent tanδ, the real part ɛ′ and imaginary part ɛ″ of the complex
permittivity, and the ac conductivity σ
ac
across the layers. It has been established that, for all gamma irradiation doses, the TlInS2 single crystal is characterized by the dielectric loss due to electrical conduction up to a frequency of 107 Hz and by the relaxation loss at a higher frequency. Irradiation of the TlInS2 single crystal results in an increase in the dispersion of tan δ, ɛ′, and ɛ″. It has been demonstrated that, as the gamma
irradiation dose is accumulated in the TlInS2 single crystal, the density of localized states near the Fermi level N
F increases (from 5.2 × 1018 to 1.9 × 1019 eV−1 cm−3). 相似文献
15.
Characteristic study of cold atmospheric argon plasma jets with rod-tube/tube high voltage electrode
Atmospheric argon plasma jets are generated with the rod-tube/tube high voltage electrode and a ring ground electrode at 8 kHz sinusoidal excitation voltage. It is found that the vibrational temperature, electronic excitation temperature, atomic oxygen density and spectral intensity with the rod-tube high voltage electrode are enhanced significantly than that with the tube high voltage electrode. The atomic oxygen density, molecular nitrogen density, and average electronic density are about magnitude of 1016 cm?3, 1015 cm?3, and 1012 cm?3 respectively, and the excited Ar, N2, OH and O are presented in the plasma plume with the rod-tube/tube high voltage electrode. 相似文献
16.
Y.V. Volk A.M. Malyarevich K.V. Yumashev V.N. Matrosov T.A. Matrosova M.I. Kupchenko 《Applied physics. B, Lasers and optics》2007,88(3):443-447
Anisotropy of the nonlinear absorption of Co2+ ions in MgAl2O4 single crystal at the wavelengths of 1.35 and 1.54 μm has been experimentally demonstrated. The experimental data are analyzed
in the framework of a phenomenological model when the Co2+ ions are described as three sets of linear dipoles oriented along the crystallographic axes. Ground-state and excited state
absorption cross-sections at 1.35 and 1.54 μm are evaluated to be σgsa=(4.0±0.3)×10-19, σesa=(3.6±0.4)×10-20 cm2 and σgsa=(5.1±0.3)×10-19, σesa=(4.6±0.4)×10-20 cm2, respectively.
PACS 42.55.Rz; 71.20.Be 相似文献
17.
Hao Wang Y. Wang J. Feng C. Ye B. Y. Wang H. B. Wang Q. Li Y. Jiang A. P. Huang Z. S. Xiao 《Applied Physics A: Materials Science & Processing》2008,93(3):681-684
High-k gate dielectric hafnium dioxide films were grown on Si (100) substrate by pulsed laser deposition at room temperature. The
as-deposited films were amorphous and that were monoclinic and orthorhombic after annealed at 500°C in air and N2 atmosphere, respectively. After annealed, the accumulation capacitance values increase rapidly and the flat-band voltage
shifts from −1.34 V to 0.449 V due to the generation of negative charges via post-annealing. The dielectric constant is in
the range of 8–40 depending on the microstructure. The I–V curve indicates that the films possess of a promising low leakage
current density of 4.2×10−8 A/cm2 at the applied voltage of −1.5 V. 相似文献
18.
Sayan Bhattacharyya Sajith Kurian S. M. Shivaprasad N. S. Gajbhiye 《Journal of nanoparticle research》2010,12(4):1107-1116
A new ternary nitride, CoMoN2, was prepared in the nanosize regime of 9.0 ± 2.0 nm, by nitridation of the precursor intermetallic nitride Co3Mo3N. XRD–Rietveld analysis revealed the presence of 0.60 (±0.02) mass % of Co impurity phase. The calculated space groups of
CoMoN2 and Co are P6
3
/mmc and Fm-3m, respectively. The N atoms lie at the interstitial sites and the 12 calculated nitrogen sites indicate the presence of a
layered structure. The XPS studies indicated the presence of the nitride and surface oxynitride/oxide phases. CoMoN2 is an interstitial nitride with Co and Mo in the zero oxidation state. The room temperature susceptibility is estimated after
subtracting the ferromagnetic contribution from cobalt and found to be 2.7 × 10−4 emu g−1 Oe−1, indicating the Pauli-paramagnetic nature. The ferromagnetic exchange interactions between the Co atoms in CoMoN2 are reduced due to the presence of Mo and N in the crystal lattice. The hysteresis loop shift 19 Oe is attributed to the
demagnetizing dipolar fields created in the soft CoMoN2 phase by the hard Co phase. 相似文献
19.
J. Lecointre D. S. Belic J. J. Jureta R. K. Janev P. Defrance 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,55(3):569-580
Absolute cross-sections have been measured for electron-impact dissociative
excitation and ionization of CD2+ leading to
formation of CD22+, CD+, C+,
D2+ and D+. The animated crossed-beams method
is applied in the energy range from the reaction threshold up to 2.5 keV.
The maximum total cross-sections are found to be (1.2±0.1)×10-17 cm2, (6.1±0.7)×10-17 cm2, (6.4±0.7)×10-17 cm2, (26.3±3.8)×10-19 cm2 and (14.9±1.4)×10-17 cm2 for
CD22+, CD+, C+,
D2+ and D+ respectively. Individual
contributions for dissociative excitation and dissociative ionization are
determined for each singly-charged product, which are of significant
interest in fusion plasma edge modelling and diagnostics. Conforming to the
scheme recently applied in the CD4+ and in the
CD3+ articles, the cross-sections are presented in
closed analytic forms convenient for implementation in plasma simulation
codes. Kinetic-energy-release distributions are determined for each ionic
fragment at selected electron energies. 相似文献
20.
J. Lecointre H. Cherkani-Hassani S. Cherkani-Hassani D. S. Belic J. J. Jureta P. Defrance 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,60(2):331-345
Absolute cross sections for electron-impact single ionization, dissociative
excitation and dissociative ionization of the ethynyl radical ion
(C2D+)^+) have been measured for electron energies ranging from the
corresponding reaction thresholds to 2.5 keV. The animated crossed
electron-ion beam experiment is used and results have been obtained for the
production of C2D2+, C2+, C2+_2^+ , CD+, C+ and
D+. The maximum of the cross section for single ionization is found to
be (2.01 ± 0.02) × 10-17 cm2, at the incident electron
energy of 105 eV. Absolute total cross sections for the various singly
charged fragments production are observed to decrease by a factor of almost
three, from the largest cross-section measured for C+, over C2+_2^+
and CD+ down to that of D+. The maxima of the cross sections are
obtained to be (14.5 ± 0.5) × 10-17 cm2 for C2+_2^+,
(12.1 ± 0.1) × 10-17 cm2 for CD+, (27.7 ±
0.2) × 10-17 cm2 for C+ and (11.1 ± 0.8) × 10-17 cm2 for D+.
The smallest cross section is measured to
be (1.50 ± 0.04) × 10-18 cm2 for the production of the
doubly charged ion C2+. Individual contributions for dissociative
excitation and dissociative ionization are determined for each
singly-charged product. The cross sections are presented in closed analytic
forms convenient for implementation in plasma simulation codes. Kinetic
energy release distributions of dissociation fragments are seen to extend
from 0 to 6 eV for the heaviest fragment C2+_2^+, up to 11.0 eV for
CD+, 14.2 eV for C+ and 11.2 eV for D+ products. 相似文献