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1.
The infrared transmissivity of heavily dopedp-type contact layers on silicon was studied in the 3–5 μm and 8–14 μm wavelength range in order to optimise the layer thickness
and doping concentration for antireflection coating. The transmissivity of surface layers and buried layers was computed taking
into account the free carrier optical dispersion by the Drude theory and corrections due to intervalence band transitions
as well as multiple reflections and interferences in the layer. The computations are in quantitative agreement with measurements
on contact layers formed by multiple boron implantation. It was found that the free carrier absorption loss completely cancels
the gain due to the antireflection effect for a surface layer. Transmissivities of around 73% may be obtained by a buried
heavily doped layer. 相似文献
2.
Summary In this paper the technique of infrared angular spectroscopy applied to the characterization of epitaxial layers ofn-type silicon grown on N+ or P+ substrates is illustrated. Some results are reported and discussed concerning films having a free-carrier concentration ranging
from 1014 cm−3 to 1017 cm−3 and thickness of the order of 10 μm. A significant comparison with results obtained by other techniques (four-point probe,
spreading resistance,C−V plots, etc.) is performed and a few simple conclusions are drawn.
To speed up publication, the authors of this paper have agreed to not receive the proofs for correction. 相似文献
3.
J. Cousin W. Chen D. Bigourd M. Fourmentin S. Kassi 《Applied physics. B, Lasers and optics》2009,97(4):919-929
We report on the development of a field deployable compact laser instrument tunable over ∼232 cm−1 from 3.16 to 3.41 μm (2932.5–3164.5 cm−1) for chemical species monitoring at the ppb-level. The laser instrument is based on widely tunable continuous-wave difference-frequency
generation (DFG), pumped by two telecom-grade fiber lasers. DFG power of ∼0.3 mW near 3.3 μm with a spectral purity of ∼3.3
MHz was achieved by using moderate pumping powers: 408 mW at 1062 nm and 636 mW at 1570 nm. Spectroscopic performance of the
developed DFG-based instrument was evaluated with direct absorption spectra of ethylene at 3.23 μm (∼3094.31 cm−1). Absorption spectra of vapor-phase benzene near 3.28 μm (∼3043.82 cm−1) were recorded with Doppler-limited resolution. Line intensities of the most intense absorption lines of the ν
12 band near 3043.8 cm−1 were determined to support development of sensitive mid-infrared trace gas detection of benzene vapor in the atmosphere.
Detection of benzene vapor in air at different concentration levels has been performed for the first time using multi-pass
cell enhanced direct absorption spectroscopy at ∼3.28 μm with a minimum detectable concentration of 50 ppb (1σ). 相似文献
4.
An analytical model of K
α radiation of thin laser targets has been developed. It has been shown that, for such targets, the motion of fast electrons
is significant not only in the target itself but also in vacuum. The considered dependences for the free path length of a
fast electron and for the absorption coefficient of laser radiation on the laser intensity with allowance for the electron
motion in vacuum make it possible to match the results of the proposed model with the experimental data on generation of K
α radiation in wide ranges of laser intensities (1018–1021 W/cm2) and thicknesses (1–100 μm) of targets. 相似文献
5.
A tunable diode laser (TDL) is used to measure the absorption spectra of the R46 through R54 transitions of the 20012←00001 band of CO2 near 2.0 μm (5000 cm−1) at room temperature and pressures to 10 atm (densities to 9.2 amagat). Spectra are recorded using direct absorption spectroscopy
and wavelength modulation spectroscopy with second-harmonic detection (WMS-2f) in a mixture containing 11% CO2 in air. The direct absorption spectra are influenced by non-Lorentzian effects including finite-duration collisions which
perturb far-wing absorption, and an empirical χ-function correction to the Voigt line shape is shown to greatly reduce error in the spectral model. WMS-2f spectra are shown
to be at least a factor of four less-influenced by non-Lorentzian effects in this region, making this approach more resistant
to errors in the far-wing line shape model and allowing a comparison between the spectral parameters of HITRAN and a new database
which includes pressure-induced shift coefficients. The implications of these measurements on practical, high-pressure CO2 sensor design are discussed. 相似文献
6.
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
7.
N. A. Nemkovich W. Baumann Yu. V. Kruchenok G. I. Kurilo V. G. Pivovarenko A. N. Rubinov 《Optics and Spectroscopy》2011,110(4):541-549
Using spectroscopy of the molecular Stark effect and fluorescence spectroscopy, we study the characteristics of diflavonol
3,7-dihydroxy-2,8-di(4-dimethylaminophenyl)-4H,6H-pyrano[3,2-g]chromene-4,6-dione (DFME), which demonstrates intramolecular charge and proton phototransfer. In the ground state, this dye
has only one form and, in the excited state, it has two forms, i.e., normal and phototautomeric. We found that, for the normal
form of DFME, the transition dipole moment that is responsible for the absorption (m
a
), the dipole moment in the equilibrium ground state (μ
g
), and the change of the dipole moment upon transition of the molecule in the excited Franck-Condon state (Δ
a
μ) are parallel. In the ground equilibrium state, the dipole moments in 1,4-dioxane and cyclohexane are equal to μg = 12.2 × 10−30 C m and μ
g
= 11.0 × 10−30 C m, respectively. Upon excitation, they increase by Δ
a
μ = 61 × 10−30 C m and Δ
a
μ = 50.2 × 10−30 C m in these solvents. We study the spectral characteristics of DFME in organic solvents and erythrocyte membranes. A spectral
inhomogeneity of DFME in erythrocyte ghosts is found. The inhomogeneous broadening of fluorescence spectra is manifested as
a long-wavelength shift of the band of the normal form of DFME by 1640 cm−1 upon excitation at the red edge of the absorption spectrum. 相似文献
8.
H. T. Chen X. L. Wu Y. Y. Zhang W. N. Su 《Applied Physics A: Materials Science & Processing》2009,97(3):725-728
Highly-pure iron powder was covered on porous silicon for fabricating semiconducting β-FeSi2 structures. X-ray diffraction and Raman scattering results confirm the formation of pure-phase β-FeSi2 after high-temperature annealing at 1100°C and then long-time persistence at 900°C. Scanning electron microscope observations
reveal that large-size (>μm) β-FeSi2 grains mainly form in the pores of porous silicon and some nanocrystals grow on local surfaces. The temperature-dependent
photoluminescence spectra disclose that the observed ∼1.54 μm emission arises from free exciton recombination, which is confirmed
via the activation energy (0.25 eV) measurement. Our method provides a way to synthesize single-phase β-FeSi2 materials. 相似文献
9.
P. Frank F. Lang M. Mosbacher J. Boneberg P. Leiderer 《Applied Physics A: Materials Science & Processing》2008,93(1):1-4
Steam Laser Cleaning with a pulsed infrared laser source is investigated. The infrared light is tuned to the absorption maximum
of water (λ=2.94 μm, 10 ns), whereas the substrates used are transparent (glass, silicon). Thus a thin liquid water layer condensed on
top of the contaminated substrate is rapidly heated. The pressure generated during the subsequent phase explosion generates
a cleaning force which exceeds the adhesion of the particles. We examine the cleaning threshold in single shot experiments
for particles sized from 1 μm down to 300 nm. 相似文献
10.
D. Fagundes-Peters A.S.S. de Camargo L.A.O. Nunes 《Applied physics. B, Lasers and optics》2006,85(1):101-104
Thulium doped fluoroindogallate glass was characterized by means of excited state absorption experiment in the 0.95 to 1.55 μm spectral range. The three bands corresponding to the electronic transitions 3
F
4→3
F
2 (at 1.05 μm), 3
F
4→3
F
3 (at 1.125 μm), and 3
F
4→3
H
4 (at 1.45 μm) were observed. The energy transfer microscopic parameters for the reverse cross relaxation process 3
F
4, 3
F
4→3
H
6, 3
H
4 were calculated for different multipolar interaction mechanisms using the Kushida model, and it was verified that the probability of this process is 100 times lower than that of the direct 3
H
4, 3
H
6→3
F
4, 3
F
4 cross relaxation, responsible for the 1.8 μm emission pumping. PACS 78.20.-e; 78.55.Qr; 42.70.Hj; 42.55.Wd 相似文献
11.
H. Keller R. F. Kiefl Hp. Baumeler W. Kündig B. D. Patterson J. Imazato K. Nishiyama K. Nagamine T. Yamazaki R. I. Grynszpan 《Hyperfine Interactions》1986,31(1-4):461-466
The hyperfine field (B
μ
hf
) at the negative muon μ− in ferromagnetic iron was investigated by means of the zero-field μ− spin precession technique. In the temperature range 320–690 K,B
μ
hf
for μ− Fe departs from the magnetization curve of pure iron in the same way as the hyperfine field seen by a55Mn impurity in dilute MnFe measured by NMR. The hyperfine anomaly for μ− Fe relative to dilute (1.5 at.%)55Mn in iron is found to be −0.9(3)% and temperature independent over the temperature range investigated. 相似文献
12.
S. A. Dyakov E. V. Astrova T. S. Perova S. G. Tikhodeev N. A. Gippius V. Yu. Timoshenko 《Journal of Experimental and Theoretical Physics》2011,113(1):80-85
The reflection spectra of grooved silicon structures consisting of alternating silicon walls and grooves (air channels) with
a period of a = 4–6 μm are studied experimentally and theoretically in the mid-IR spectral range (2–25 μm) upon irradiation of samples
by normally incident light polarized along and perpendicular to silicon layers. The calculation is performed by the scattering
matrix method taking into account Rayleigh scattering losses in a grooved layer by adding imaginary parts to the refractive
indices of silicon and air in grooved regions. The experimental and calculated reflection spectra are in good agreement in
the entire spectral range studied. The analysis of experimental and calculated spectra gave close values of the effective
refractive indices and birefringence of the studied structures in the long-wavelength spectral region. The values calculated
in the effective medium model in the long-wavelength approximation (λ ≫ a) gave considerably understated values. The obtained results confirm the efficiency of the scattering matrix method for describing
the optical properties of silicon microstructures. 相似文献
13.
F. V. Kharlamov V. F. Kharlamov 《Russian Journal of Physical Chemistry B, Focus on Physics》2010,4(3):391-398
It was found that, if the energy released in the formation of product molecules in a heterogeneous reaction was smaller than
the work function of the surface, the current density of the chemiemission of electrons from the surface of any semiconductor
satisfied the condition j ≈ Bexp(βE), where B and β are coefficients and E is the electric field in the semiconductor surface plane. A mathematical model describing the transfer of hot metal electrons
excited in a catalytic reaction through the metal-gas interphase boundary was studied. The parameters of the system at which
a study of the distribution of catalytic centers over the surface of a metal or semiconductor by the scanning tip method on
the basis of the chemiemission of electrons stimulated by an electric field was possible (resolution δr ∼ 10−8–10−7 m) were determined. Theoretical results corresponded to the experimental data obtained using weak electric fields (0 < E < 5 × 106 V/m) for the heterogeneous recombination of hydrogen atoms on the surface of calcium, titanium, and n-type silicon. 相似文献
14.
A novel two-wavelength mid-infrared laser-absorption diagnostic has been developed for simultaneous measurements of vapor-phase
fuel mole fraction and liquid fuel film thickness. The diagnostic was demonstrated for time-resolved measurements of n-dodecane liquid films in the absence and presence of n-decane vapor at 25°C and 1 atm. Laser wavelengths were selected from FTIR measurements of the C–H stretching band of vapor
n-decane and liquid n-dodecane near 3.4 μm (3000 cm−1). n-Dodecane film thicknesses <20 μm were accurately measured in the absence of vapor, and simultaneous measurements of n-dodecane liquid film thickness and n-decane vapor mole fraction (300 ppm) were measured with <10% uncertainty for film thicknesses <10 μm. A potential application
of the measurement technique is to provide accurate values of vapor mole fraction in combustion environments where strong
absorption by liquid fuel or oil films on windows make conventional direct absorption measurements of the gas problematic. 相似文献
15.
Tunable diode-laser absorption of CO2 near 2.7 μm incorporating wavelength modulation spectroscopy with second-harmonic detection (WMS-2f) is used to provide a
new sensor for sensitive and accurate measurement of the temperature behind reflected shock waves in a shock-tube. The temperature
is inferred from the ratio of 2f signals for two selected absorption transitions, at 3633.08 and 3645.56 cm−1, belonging to the ν
1+ν
3 combination vibrational band of CO2 near 2.7 μm. The modulation depths of 0.078 and 0.063 cm−1 are optimized for the target conditions of the shock-heated gases (P∼1–2 atm, T∼800–1600 K). The sensor is designed to achieve a high sensitivity to the temperature and a low sensitivity to cold boundary-layer
effects and any changes in gas pressure or composition. The fixed-wavelength WMS-2f sensor is tested for temperature and CO2 concentration measurements in a heated static cell (600–1200 K) and in non-reactive shock-tube experiments (900–1700 K) using
CO2–Ar mixtures. The relatively large CO2 absorption strength near 2.7 μm and the use of a WMS-2f strategy minimizes noise and enables measurements with lower concentration,
higher accuracy, better sensitivity and improved signal-to-noise ratio (SNR) relative to earlier work, using transitions in
the 1.5 and 2.0 μm CO2 combination bands. The standard deviation of the measured temperature histories behind reflected shock waves is less than 0.5%.
The temperature sensor is also demonstrated in reactive shock-tube experiments of n-heptane oxidation. Seeding of relatively
inert CO2 in the initial fuel-oxidizer mixture is utilized to enable measurements of the pre-ignition temperature profiles. To our
knowledge, this work represents the first application of wavelength modulation spectroscopy to this new class of diode lasers
near 2.7 μm. 相似文献
16.
H. Simmler P. Eschle H. Keller W. Kündig W. Odermatt B. D. Patterson B. Pümpin I. M. Savić J. W. Schneider U. Straumann P. Truöl 《Hyperfine Interactions》1991,64(1-4):535-541
Planar channeling data ofμ
+-decay positrons in various semiconductors are reported. Together with the extensive spectroscopic data supplied by transverse
μSR, the location of the different states of the hydrogen pseudo-isotopeμ
+ e− (muonium) can be identified by means of planar simulations. In high purity silicon as well as in gallium arsenide a thermally
activated site transition is observed which can be assigned to a transition between different muonium states. 相似文献
17.
I. Sokólska 《Applied physics. B, Lasers and optics》2000,71(2):157-162
LaGaO3 crystals doped with Er3+ ions were grown by the Czochralski method and their optical properties were examined. The Er3+ energy levels have been determined from the low-temperature absorption and emission spectra. The results of Judd–Ofelt analysis
are presented and compared with experimental data. The emission cross sections are determined for the 4
I
13/2→4
I
15/2 (1.55 μm) and 4
I
11/2→4
I
13/2 (2.85 μm) transitions of erbium.
Received: 6 December 1999 / Revised version: 10 February 2000 / Published online: 27 April 2000 相似文献
18.
Spectral dependences of the coefficients of absorption by free carriers and of multiphoton absorption by a silicon lattice
in the region of the interstitial oxygen band at 5.8 μm are established. A procedure for measurement of the distribution of
oxygen and alloying impurities in silicon ingots is given. The effectiveness of the spectrometers developed for controlling
the segregation of impurities and nonstationary convection of the silicon melt in growing ingots by the Czochralski method
is shown.
Belarusian State University, 4, F. Skorina Ave., Minsk, 220080, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii,
Vol. 64, No. 5, pp. 655–659, September–October, 1997. 相似文献
19.
《Applied physics. B, Lasers and optics》1981,24(1):33-38
We report infrared laser emission in the region of 3 to 5 μm from sodium vapour optically pumped by a pulsed dye laser with
wavelengths ranging from 585 to 610nm. Twophoton excitation processes are believed to be responsible for the primary excitation.
Both molecular transitions (4 to 5 μm) between high lying states, and atomic transitions (52
S
1/2−42
P
3/2,1/2 at 3.41 μm) have been identified. 相似文献
20.
V. V. Filippov V. V. Kuznetsova V. S. Khomenko P. P. Pershukevich V. P. Bondarenko 《Journal of Applied Spectroscopy》1999,66(3):464-469
Er3+ and Yb3+ ions are introduced into porous silicon films, stabilized by oxidation in an oxygen plasma, in the form of a gadolinium oxychloride-based
luminophor by means of thermal diffusion. An investigation is made of the luminescence and photoexcitation spectra of samples
with Er3+ (10 and 30 wt.%), Yb3+ (10 wt.%), and Er3, Yb3++ (10 wt.% each). It is shown that the intense IR luminescence (1.00 and 1.54 μm) is caused by cross-relaxation effects. The
most effective excitation of the luminescence has been observed in the UV absorption band of the porous silicon.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 3, pp. 428–433, May–June, 1999. 相似文献