共查询到20条相似文献,搜索用时 109 毫秒
1.
SrZr1−x
Y
x
O3 coatings were co-sputtered from metallic Zr–Y (84–16 at.%) and Sr targets in the presence of a reactive argon–oxygen gas
mixture. The structural and chemical features of the film have been assessed by X-ray diffraction and scanning electron microscopy.
The electrical properties have been investigated for different substrates by Complex Impedance Spectroscopy as a function
of crystalline state, temperature and atmosphere. The as-deposited coatings are amorphous and crystallise after annealing
at 673 K for 2 h under air. The stabilisation of the perovskite structure is a function of the nominal composition. The films
are dense and present a good adhesion on different substrates. Crystallisation and mechanical stresses are detected by alternating
current (AC) impedance spectroscopy. Significant ionic conductivity in the 473–823 K temperature range is evidenced in air.
Two different conduction regimes in the presence of steam are attributed to a modification of the charge carrier nature. In
spite of low conductivity values (σ ~10−6 S.cm−1 at 881 K), the activation energies are in agreement with that of Y-doped strontium zirconate ceramics (~0.7 eV in air). 相似文献
2.
Krzysztof?Idzik Jadwiga?So?oducho Mieczys?aw??apkowski Przemys?aw?Data 《Journal of fluorescence》2010,20(5):1069-1075
Novel light-emitting organic materials comprising conjugated oligomers chemically attached via a flexible spacer to an electron–or hole-conducting core were synthesized by Stille cross-coupling methodology and designed for tunable charge injection and optical properties. The hyperbranched structures
have been characterized by 1H NMR, 13C NMR, and UV-VIS spectroscopy. The obtained structures show good stability in common organic solvents such as CHCl3, toluene, and CH2Cl2 and exhibit excellent thermal stability. A preliminary electroluminescence properties were also investigated. This class
of materials will help to balance charge injection and transport and to spread out the charge recombination zone, thereby
significantly improving the device efficiency and lifetime of unpolarized and polarized OLEDs. 相似文献
3.
Yuechun Fu Xuefei Li Yunyun Wang Huan He Xiaoming Shen 《Applied Physics A: Materials Science & Processing》2012,106(4):937-940
Cubic AlN films were successfully deposited on TiN buffered Si (100) substrates by a laser molecular beam epitaxy (LMBE) technique,
and their crystal structure and optical and electrical properties were studied. The results indicate that cubic AlN films
show the NaCl-type structure with a (200) preferred orientation, and the lattice parameter is determined to be 0.4027 nm.
The Fourier transform infrared (FTIR) pattern of the cubic AlN film displays sharp absorption peaks at 668 cm−1 and 951 cm−1, corresponding to the transverse and longitudinal optical vibration modes. Ellipsometric measurements evidence a refractive
index of 1.66–1.71 and an extinction coefficient of about zero for the cubic AlN film in the visible range. Capacitance–voltage
(C–V) traces of the metal–insulator–semiconductor (MIS) device exhibit that the cubic AlN film has a dielectric constant of 8.1,
and hysteresis in the C–V traces indicates a significant number of charge traps in the film. 相似文献
4.
R. Castro-Beltran G. Ramos-Ortiz C. K. W. Jim J. L. Maldonado M. H?u?ler D. Peralta-Dominguez M. A. Meneses-Nava O. Barbosa-Garcia B. Z. Tang 《Applied physics. B, Lasers and optics》2009,97(2):489-496
The nonlinear optical properties of a hyperbranched polyyne (hb-Polyyne) have been measured at infrared wavelengths by using femtosecond and nanosecond pulsed excitation. This hyperbranched
polyyne exhibited strong and intrinsic (simultaneous) two-photon absorption and upconverted blue fluorescent emission under
femtosecond excitation around 800 nm. The hb-Polyyne in chloroform solution is characterized by a large two-photon absorption cross section of 9068 GM (1GM=10−50 cm4 s) and a fluorescence quantum yield of 0.57. On the other hand, by third-harmonic generation (THG) spectroscopy with nanosecond
excitation, the measured third-order nonlinear susceptibility χ
(3) for solid films of hb-Polyyne ranged from 2.4×10−11 to 6.1×10−11 esu in the spectral range of 1100–1600 nm, with results comparable to the values exhibited by the well-known conjugated polymer
MEH:PPV, but with a much better transparency for visible wavelengths. 相似文献
5.
X. Y. Tao I. Fsaifes V. Koncar C. Dufour C. Lepers L. Hay B. Capoen M. Bouazaoui 《Applied Physics A: Materials Science & Processing》2009,96(3):741-749
Indium tin oxide (ITO) thin films prepared by the sol–gel method have been deposited by the dip-coating process on silica substrates. CO2 laser is used for annealing treatments. The electrical resistivity of sol–gel-derived ITO thin films decreased following
crystallization after exposure to CO2 laser beam. The topological and electrical properties of the irradiated surfaces have been demonstrated to be strongly related
to the coating solution and to the laser processing parameters. Optimal results have been obtained for 5 dip-coating layers
film from 0.4 mol/l solution irradiated by 0.6 W/m2 laser power density. In this case, homogeneous and optically transparent traces were obtained with a measured sheet resistance
of 1.46×102 Ω/□. 相似文献
6.
S. Guha D. Adil N. B. Ukah R. K. Gupta K. Ghosh 《Applied Physics A: Materials Science & Processing》2011,105(3):547-554
Matrix-assisted pulsed-laser evaporation (MAPLE) provides a mechanism for layer-by-layer growth to control the polymer–dielectric
interface in organic metal–insulator–semiconductor (MIS) diodes and field-effect transistors (FETs). MAPLE-deposited copolymers
of polyfluorene (PF) and polythiophene maintain their structural and optical properties, as determined by Raman spectroscopy,
absorption, and photoluminescence. These films are further utilized in MIS and FET structures with SiO2 and other polymer dielectrics. Since common polymer dielectrics prevent spin coating of solution processable polymers due
to solubility effects, MAPLE is one of the only deposition techniques for investigating all polymer semiconductor-insulator
interfaces. In this paper we present optical and electrical studies of MAPLE-deposited PF and polythiophene films in FETs
and MIS structures. The FET carrier mobilities of these devices compare well with spin-coated devices. Capacitance–voltage
and conductance–voltage from MIS structures with MAPLE-deposited PF copolymer films yield interface trap densities in the
low 1012 eV−1 cm−2 range. 相似文献
7.
Germania/γ-glycidoxypropyltrimethoxysilane organic–inorganic hybrid spin-coating thin films doped with neodymium ions are prepared by a sol–gel technique and a spin-coating process. Acid-catalyzed solutions of γ-glycidoxypropyltrimethoxysilane mixed with germanium isopropoxide are used as matrix precursors. Thermal gravimetric analysis, UV–visible spectroscopy, and Fourier transform infrared spectroscopy are used to study the structural and optical properties of the hybrid thin films. The results indicate that films that are crack-free and have a high transparency in the visible and near-infrared range can be obtained; a strong UV absorption region at short wavelength ∼200 nm, accompanied with a shoulder peaked at ∼240 nm, due to the neutral oxygen monovacancy defects, is also identified. Upconversion emission properties of the transparent dried gel and the thin films heated at different heat treatment temperatures and doped with different neodymium ion concentrations are studied; a relatively strong room-temperature yellow to violet upconversion emission at 397 nm (4
D
3/2→4
I
13/2) is observed under a xenon lamp excitation with yellow light at the wavelength of 580 nm (4
I
9/2→4
G
5/2). The effect of Nd3+ doping concentration and heat treatment temperature on upconversion emission of the thin films is also studied. The mechanism of the upconversion is proposed. PACS 81.05.Kf; 81.20.Fw; 78.55.Hx 相似文献
8.
Tin oxide (SnO2) thin films have been grown on glass substrates using atmospheric pressure chemical vapour deposition (APCVD) method. During
the deposition, the substrate temperature was kept at 400°C–500°C. The structural properties, surface morphology and chemical
composition of the deposited film were studied by X-ray diffraction (XRD), scanning electron microscope (SEM) and Rutherford
back scattering (RBS) spectrum. XRD pattern showed that the preferred orientation was (110) having tetragonal structure. The
optical properties of the films were studied by measuring the transmittance, absorbance and reflectance spectra between λ = 254 nm to 1400 nm and the optical constants were calculated. Typical SnO2 film transmits ∼ 94% of visible light. The electrical properties of the films were studied using four-probe method and Hall-voltage
measurement experiment. The films showed room temperature conductivity in the range 1.08 × 102 to 1.69 × 102 Ω−1cm−1. 相似文献
9.
A sodium ion conducting composite polymer electrolyte (CPE) prepared by solution-caste technique by dispersion of an electrochemically
inert ceramic filler (SnO2) in the PEO–salt complex matrix is reported. The effect of filler concentration on morphological, electrical, electrochemical,
and mechanical stability of the CPE films has been investigated and analyzed. Composite nature of the films has been confirmed
from X-ray diffraction and scanning electron microscopy patterns. Room temperature d.c. conductivity observed as a function
of filler concentration indicates an enhancement (maximum) at 1–2 wt% filler concentration followed by another maximum at
∼10 wt% SnO2. This two-maxima feature of electrical conductivity as a function of filler concentration remains unaltered in the CPE films
even at 100 °C (i.e., after crystalline melting), suggesting an active role of the filler particles in governing electrical
transport. Substantial enhancement in the voltage stability and mechanical properties of the CPE films has been noticed on
filler dispersion. The composite polymer films have been observed to be predominantly ionic in nature with t
ion ∼ 0.99 for 1–2 wt% SnO2. However, this value gets lowered on increasing addition of SnO2 with t
ion ∼ 0.90 for 25 wt% SnO2. A calculation of ionic and electronic conductivity for 25 wt% of SnO2 film works out to be ∼2.34 × 10−6 and 2.6 × 10−7 S/cm, respectively. 相似文献
10.
The Ac electrical conductivity and the dielectric relaxation properties of the [(C3H7)4N]2Cd2Cl6 polycrystalline sample have been investigated by means of impedance spectroscopy measurements over a wide range of frequencies
and temperatures, 209 Hz–5 MHz and 361–418 K, respectively. The purpose is to make a difference between the electrical and
dielectric properties of the polycrystalline sample and single crystal. Besides, a detailed analysis of the impedance spectrum
suggests that the electrical properties of the material are strongly temperature-dependent. Plots of (Z" versus Z') are well
fitted to an equivalent circuit model consisting of a series combination of grains and grains boundary elements. Moreover,
the temperature dependence of the electrical conductivity in the different phases follows the Arrhenius law and the frequency
dependence of σ (ω) follows the Jonscher’s universal dynamic law. Furthermore, the modulus plots can be characterized by full
width at half height or in terms of a nonexperiential decay function φ(t) = exp(t/t)β. Finally, the imaginary part of the permittivity constant is analyzed with the Cole–Cole formalism. 相似文献
11.
Determination of the optimal parameters for the fabrication of ZnO thin films prepared by spray pyrolysis method 总被引:1,自引:0,他引:1
In this work, ZnO thin films have been prepared by spray pyrolysis deposition method on the glass substrates. The effect of
deposition parameters, such as deposition rate, substrate temperature and solution volume has been studied by X-ray diffraction
(XRD) method, UV–Vis–NIR spectroscopy, scanning electron microscopy (SEM), and electrical measurements. The XRD patterns indicate
polycrystalline wurtzite structure with preferred direction along (0 0 2) planes. Thin films have transparency around 90%
in the visible range. The optical band gap was determined at 3.27 eV which did not change significantly. Evolution of electrical
results containing the carriers’ density, sheet resistance and resistivity are in agreement with structural results. All the
results suggest the best deposition parameters are: deposition rate, R = 3 ml/min, substrate temperature, T
s = 450°C and thickness of the thin films t = 110–130 nm. 相似文献
12.
AMBIKA NEGI R V HARIWAL ANJU SEMWAL R G SONKAWEDE D KANJILAL J M S RANA R C RAMOLA 《Pramana》2011,77(4):707-714
In the present study, the effects of swift heavy ion beam irradiation on the structural, chemical and optical properties of
Makrofol solid-state nuclear track detector (SSNTD) were investigated. Makrofol-KG films of 40 μm thickness were irradiated with oxygen beam (O8 + ) with fluences ranging between 1010 ion/cm2 and 1012 ion/cm2. Structural, chemical and optical properties were investigated using X-ray diffraction, FTIR spectroscopy and UV–visible
spectroscopy methods. It is observed that the direct and indirect band gaps of Makrofol-KG decrease after the irradiation.
The XRD study shows that the crystalline size in the films decreases at higher fluences. The intensity plots of FTIR measurements
indicate the degradation of Makrofol at higher fluences. Roughness of the surface increases at higher fluence. 相似文献
13.
Ytterbium vapor condensation on a liquid-helium cooled substrate in a hydrogen atmosphere is used to obtain Yb-H films containing
up to 55 at.% hydrogen. Various thermodynamic and kinetic parameters of the transition of these films from the amorphous to
the crystalline state (a→c transition) are investigated along with the electrical conductivity of these states. It is shown that the investigated properties
of Yb-H films containing up to 40 at.% hydrogen are essentially indistinguishable from those of pure Yb films in the temperature
interval 4.2–293 K. Increasing the hydrogen concentration to 55 at.% leads to an insignificant increase in the electrical
resistivity, the kinetic temperature, and the activation energy of the a→c transition, and also to a decrease of the propagation speed of self-maintaining avalanche (explosive) crystallization. Reasons
for the observed influence of hydrogen on the properties of Yb-H films are analyzed. The examined low-temperature Yb-H condensates
can be characterized as a “frozen” solid solution of hydrogen in ytterbium in the temperature interval 4.2–293 K. Storing
such films at room temperature leads to the formation of ionic ytterbium dihydride YbH2.
Fiz. Tverd. Tela (St. Petersburg) 41, 177–182 (February 1999) 相似文献
14.
S. Y. Huang S. Xu Q. J. Cheng J. D. Long K. Ostrikov 《Applied Physics A: Materials Science & Processing》2009,97(2):375-380
Aluminum-doped p-type polycrystalline silicon thin films have been synthesized on glass substrates using an aluminum target
in a reactive SiH4+Ar+H2 gas mixture at a low substrate temperature of 300 °C through inductively coupled plasma-assisted RF magnetron sputtering.
In this process, it is possible to simultaneously co-deposit Si–Al in one layer for crystallization of amorphous silicon,
in contrast to the conventional techniques where alternating metal and amorphous Si layers are deposited. The effect of aluminum
target power on the structural and electrical properties of polycrystalline Si films is analyzed by X-ray diffraction, Raman
spectroscopy, scanning electron microscopy and Hall-effect analysis. It is shown that at an aluminum target power of 100 W,
the polycrystalline Si film features a high crystalline fraction of 91%, a vertically aligned columnar structure, a sheet
resistance of 20.2 kΩ/□ and a hole concentration of 6.3×1018 cm−3. The underlying mechanism for achieving the semiconductor-quality polycrystalline silicon thin films at a low substrate temperature
of 300 °C is proposed. 相似文献
15.
Gilho Kim Jungsik Bang Yunseok Kim S. K. Rout Seong Ihl Woo 《Applied Physics A: Materials Science & Processing》2009,97(4):821-828
Zn1−x
B
x
O (0≤x≤0.04) thin films were deposited by the liquid source misted chemical vapor deposition (LSMCD) method. The thin films were
polycrystalline with grain sizes of 16 nm to 22 nm. The structural, optical, and electrical properties were investigated by
X-ray diffraction, UV-visible spectrophotometry, Raman spectroscopy, and Hall effect measurement. Also scanning electron (SEM)
and atomic force microscopy (AFM) techniques were used in order to determine the morphological and topological characteristics
of the films. The optimal result of Zn1−x
B
x
O films was obtained at x=0.02, with a low resistivity of ≈10−2 Ω cm, and a high transmittancy of 85% in the visible light spectrum (300 nm ∼ 800 nm). 相似文献
16.
H. Kim G. P. Kushto R. C. Y. Auyeung A. Piqué 《Applied Physics A: Materials Science & Processing》2008,93(2):521-526
Fluorine-doped tin oxide (FTO) thin films have been investigated as an alternative to indium tin oxide anodes in organic photovoltaic
devices. The structural, electrical, and optical properties of the FTO films grown by pulsed laser deposition were studied
as a function of oxygen deposition pressure. For 400 nm thick FTO films deposited at 300°C and 6.7 Pa of oxygen, an electrical
resistivity of 5×10−4 Ω-cm, sheet resistance of 12.5 Ω/□, average transmittance of 87% in the visible range, and optical band gap of 4.25 eV were obtained. Organic photovoltaic (OPV)
cells based on poly(3-hexylthiophene)/[6,6]-phenyl-C61-butyric acid methyl ester bulk heterojunctions were prepared on FTO/glass electrodes and the device performance was investigated as a function of FTO
film thickness. OPV cells fabricated on the optimum FTO anodes (∼300–600 nm thick) exhibited power conversion efficiencies
of ∼3%, which is comparable to the same device made on commercial ITO/glass electrodes (3.4%). 相似文献
17.
H. Kim A. Cepler C. Cetina D. Knies M. S. Osofsky R. C. Y. Auyeung A. Piqué 《Applied Physics A: Materials Science & Processing》2008,93(3):593-598
Present p-type ZnO films tend to exhibit high resistivity and low carrier concentration, and they revert to their natural n-type state
within days after deposition. One approach to grow higher quality p-type ZnO is by codoping the ZnO during growth. This article describes recent results from the growth and characterization
of Zr–N codoped p-type ZnO thin films by pulsed laser deposition (PLD) on (0001) sapphire substrates. For this work, both N-doped and Zr–N
codoped p-type ZnO films were grown for comparison purposes at substrate temperatures ranging between 400 to 700 °C and N2O background pressures between 10−5 to 10−2 Torr. The carrier type and conduction were found to be very sensitive to substrate temperature and N2O deposition pressure. P-type conduction was observed for films grown at pressures between 10−3 to 10−2 Torr. The Zr–N codoped ZnO films grown at 550 °C in 1×10−3 Torr of N2O show p-type conduction behavior with a very low resistivity of 0.89 Ω-cm, a carrier concentration of 5.0×1018 cm−3, and a Hall mobility of 1.4 cm2 V−1 s−1. The structure, morphology and optical properties were also evaluated for both N-doped and Zr–N codoped ZnO films. 相似文献
18.
Iron oxide films were deposited on <100> Si substrates by reactive pulsed laser deposition (RPLD) using a KrF laser (248 nm).
These films were deposited too by laser (light) chemical vapor deposition (LCVD) using continuous ultraviolet photodiode radiation
(360 nm). The deposited films demonstrated semiconducting properties. These films had large thermo-electromotive force (e.m.f.)
coefficient (S) and high photosensitivity (F). For films deposited by RPLD the S coefficient varied in the range 0.8–1.65 mV/K at 205–322 K. This coefficient depended on the band gap (E
g
) of the semiconductor films, which varied in the range 0.43–0.93 eV. The largest F value found was 44 Vc/W for white light at power density I≅0.006 W/cm2. Using LCVD, iron oxide films were deposited from iron carbonyl vapor. For these films, the S coefficient varied in the range −0.5 to 1.5 mV/K at 110–330 K. The S coefficient depended on E
g
of the semiconductor films, which varied in the range 0.44–0.51 eV. The largest F value of these films was about 40 Vc/W at the same I≅0.006 W/cm2. Our results showed that RPLD and LCVD can be used to synthesize iron oxide thin films with variable stoichiometry and, consequently,
with different values of E
g
. These films have large S coefficient and high photosensitivity F and therefore can be used as multi-parameter sensors: thermo–photo sensors. 相似文献
19.
Latha Kumari S. V. Subramanyam 《Applied Physics A: Materials Science & Processing》2009,95(2):343-349
Amorphous carbon–sulfur (a-C:S) composite films were prepared by vapor phase pyrolysis technique. The structural changes in
the a-C:S films were investigated by electron microscopy. A powder X-ray diffraction (XRD) study depicts the two-phase nature
of a sulfur-incorporated a-C system. The optical bandgap energy shows a decreasing trend with an increase in the sulfur content
and preparation temperature. This infers a sulfur incorporation and pyrolysis temperature induced reduction in structural
disorder or increase in sp
2 or π-sites. The presence of sulfur (S 2p) in the a-C:S sample is analyzed by the X-ray photoelectron spectroscopy (XPS). The sp
3/sp
2 hybridization ratio is determined by using the XPS C 1s peak fitting, and the results confirm an increase in sp
2 hybrids with sulfur addition to a-C. The electrical resistivity variation in the films depends on both the sulfur concentration
and the pyrolysis temperature. 相似文献
20.
We report the ac conductivity and relaxation behavior analysis for a heterogeneous polymer–clay nanocomposite (PNC) having
composition (polyacrylonitrile)8LiCF3SO3 + x wt.% dodecylamine modified montmorillonite. Charge transport behavior in an ionically conducting PNC has been analyzed systematically
and correlated with the macroscopic parameters like polymer glass transition temperature and available free mobile charge
carriers. Intercalation of cation coordinated polymer into the nanometric clay channels has been confirmed by high-resolution
transmission electron microscopy. The electrical properties of the intercalated PNC films have been studied using complex
impedance/admittance spectroscopy. Excellent correlation of relaxation behavior with polymer glass transition temperature
(T
g) confirmed the objectives of the work. An analysis of dielectric relaxation indicates that PNC films are lossy when compared
with polymer–salt film. This result is a direct outcome of faster ion dynamics leading to strong electrode polarization effect
due to the accumulation of charge carriers at the interface. 相似文献