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1.
Transparent films of copper yttrium oxide doped with 2% calcium have been prepared by rf magnetron sputtering. The films show
a conductivity of 8 Scm−1 on intercalation of oxygen at high pressure, which reduced the transparency in the visible region. The Ca-doped CuYO2 films before oxygen intercalation show an average transmission of about 60% which reduces to about 45% upon oxygen intercalation.
The temperature dependence of the conductivity indicates semiconductor behaviour with low activation energy of 0·59 eV at
room temperature. The positive sign of Seebeck coefficient (+274 μVK−1) confirms the p-type conductivity of the films. The optical bandgap of CuYO2 was found to be 3·15 eV. 相似文献
2.
A large number of thin films of cadmium oxide have been prepared on glass substrates by spray pyrolysis method. The prepared
films have uniform thickness varying from 200–600 nm and good adherence to the glass substrate. A systematic study has been
made on the influence of thickness on resistivity, sheet resistance, carrier concentration and mobility of the films. The
resistivity, sheet resistance, carrier concentration and mobility values varied from 1·56–5·72×10−3 Ω-cm, 128–189 Ω/□, 1·6–3·9×1021 cm−3 and 0·3–3 cm2/Vs, respectively for varying film thicknesses. A systematic increase in mobility with grain size clearly indicates the reduction
of overall scattering of charge carriers at the grain boundaries. The large concentration of charge carriers and low mobility
values have been attributed to the presence of Cd as an impurity in CdO microcrystallites. Using the optical transmission
data, the band gap was estimated and found to vary from 2·20–2·42 eV. These films have transmittance around 77% and average
reflectance is below 2·6% in the spectral range 350–850 nm. The films aren-type and polycrystalline in nature. SEM micrographs of the CdO films were taken and the films exhibit clear grains and grain
boundary formation at a substrate temperature as low as 523 K. 相似文献
3.
Thin films of molybdenum oxide were formed on glass and silicon substrates by sputtering of molybdenum target under various
sputtering powers in the range 2.3–6.8 W/cm2, at a constant oxygen partial pressure of 2 × 10−4 mbar and substrate temperature 523 K employing DC magnetron sputtering technique. The effect of sputtering power on the core
level binding energies, chemical binding configurations, crystallographic structure, surface morphology and electrical and
optical properties was systematically studied. X-ray photoelectron spectroscopic studies revealed that the films formed at
sputtering powers less than 5.7 W/cm2 were mixed oxidation states of Mo5+ and Mo6+. The films formed at 5.7 W/cm2 contained the oxidation state Mo6+ of MoO3. Fourier transform infrared spectra contained the characteristic optical vibrations. The presence of a sharp absorption band
at 1,000 cm−1 in the case of the films formed at 5.7 W/cm2 was also conformed the existence of α-phase MoO3. X-ray diffraction studies also confirmed that the films formed at sputtering powers less than 5.7 W/cm2 showed the mixed phase of α-and β-phase of MoO3 where as at sputtering power of 5.7 W/cm2 showed single phase α-MoO3. The electrical conductivity of the films increased from 8 × 10−6 to 1.2 × 10−4 Ω−1 cm−1, the optical band gap decreased from 3.28 to 3.12 eV and the refractive index decreased from 2.12 to 1.94 with the increase
of sputtering power from 2.3 to 6.8 W/cm2, respectively. 相似文献
4.
M. Öztaş M. Bedir R. Kayalı F. Aksoy 《Journal of Materials Science: Materials in Electronics》2006,17(10):841-845
InP thin films were prepared by spray pyrolysis technique using aqueous solutions of InCl3 and Na2HPO4, which were atomized with compressed air as carrier gas. The InP thin films were obtained on glass substrates. Thin layers
of InP have been grown at various substrate temperatures in the range of 450–525°C. The structural properties have been determined
by using X-ray diffraction (XRD). The changes observed in the structural phases during the film formation in dependence of
growth temperatures are reported and discussed. Optical properties, such as transmission and the band gap have been analyzed.
An analysis of the deduced spectral absorption of the deposited films revealed an optical direct band gap energy of 1.34–1.52 eV
for InP thin films. The InP films produced at a substrate temperature 500°C showed a low electrical resistivity of 8.12 × 103 Ω cm, a carrier concentration of 11.2 × 1021 cm−3, and a carrier mobility of 51.55 cm2/Vs at room temperature. 相似文献
5.
A. Sivasankar Reddy P. Sreedhara Reddy S. Uthanna G. Mohan Rao 《Journal of Materials Science: Materials in Electronics》2006,17(8):615-620
Thin films of copper aluminum oxide (CuAlO2) were prepared on glass substrates by dc magnetron sputtering at a substrate temperature of 523 K under various oxygen partial
pressures in the range 1 × 10−4–3 × 10−3 mbar. The dependence of cathode potential on the oxygen partial pressure was explained in terms of oxidation of the sputtering
target. The influence of oxygen partial pressure on the structural, electrical and optical properties was systematically studied.
p-Type CuAlO2 films with polycrystalline nature, electrical resistivity of 3.1 Ω cm, Hall mobility of 13.1 cm2 V−1 s−1 and optical band gap of 3.54 eV were obtained at an oxygen partial pressure of 6 × 10−4 mbar. 相似文献
6.
In this study, polycrystalline AgGaS2 thin films were deposited by the sequential evaporation of AgGaS2 and Ag sources with thermal evaporation technique. Thermal treatment in nitrogen atmosphere for 5 min up to 700 °C was applied
to the deposited thin films and that resulted in the mono phase AgGaS2 thin films without the participation of any other minor phase. Structural and compositional analyses showed the structure
of the films completely changes with annealing process. The measurements of transmittance and reflectance allowed us to calculate
the band gap of films lying in 2.65 and 2.79 eV depending on annealing temperature. The changes in the structure with annealing
process also modify the electrical properties of the films. The resistivity of the samples varied in between 2 × 103 and 9 × 106 (Ω-cm). The room temperature mobility depending on the increasing annealing temperature was in the range of 6.7–37 (cm2 V−1 s−1) with the changes in carrier concentrations lying in 5.7 × 1013–2.5 × 1010 cm−3. Mobility-temperature dependence was also analyzed to determine the scattering mechanisms in the studied temperature range
with annealing. The variations in the electrical parameters of the films were discussed in terms of their structural changes. 相似文献
7.
Transparent and conducting SnO2 films are prepared at 500°C on quartz substrates by chemical vapour deposition technique, involving oxidation of SnCl2. The effect of oxygen gas flow rate on the properties of SnO2 films is reported. Oxygen with a flow rate from 0·8–1·35 lmin−1 was used as both carrier and oxidizing gas. Electrical and optical properties are studied for 150 nm thick films. The films
obtained have a resistivity between 1·72 × 10−3 and 4·95 × 10−3 ohm cm and the average transmission in the visible region ranges 86–90%. The performance of these films was checked and the
maximum figure of merit value of 2·03 × 10−3 ohm−1 was obtained with the films deposited at the flow rate of 1·16 lmin−1. 相似文献
8.
The present work deals with the mixing of iron and silicon by swift heavy ions in high-energy range. The thin film was deposited
on a n-Si (111) substrate at 10−6 torr and at room temperature. Irradiations were undertaken at room temperature using 120 MeV Au+9 ions at the Fe/Si interface to investigate ion beam mixing at various doses: 5 × 1012 and 5 × 1013 ions/cm2. Formation of different phases of iron silicide has been investigated by X-ray diffraction (XRD) technique, which shows enhancement
of intermixing and silicide formation as a result of irradiation. I-V measurements for both pristine and irradiated samples have been carried out at room temperature, series resistance and barrier
heights for both as deposited and irradiated samples were extracted. The barrier height was found to vary from 0·73–0·54 eV.
The series resistance varied from 102·04–38·61 kΩ. 相似文献
9.
Dhananjay Kumar K M Satyalakshmi S S Manoharan M S Hegde 《Bulletin of Materials Science》1994,17(6):625-632
Microstructural and superconducting properties of YBa2Cu3O7−x
thin films grownin situ on bare sapphire by pulsed laser deposition using YBa2Cu3O7−x
targets doped with 7 and 10 wt% Ag have been studied. Ag-doped films grown at 730°C on sapphire have shown very significant
improvement over the undoped YBa2Cu3O7−x
films grown under identical condition. A zero resistance temperature of 90 K and a critical current density of 1·2×106 A/cm2 at 77 K have been achieved on bare sapphire for the first time. Improved connectivity among grains and reduced reaction rate
between the substrate and the film caused due to Ag in the film are suggested to be responsible for this greatly improved
transport properties. 相似文献
10.
K. H. Kang H. S. Moon K. C. Song M. S. Yang S. H. Lee S. W. Kim 《International Journal of Thermophysics》2007,28(5):1595-1606
The thermal diffusivity of a simulated fuel with fission products forming a solid solution was measured using the laser-flash
method in the temperature range from room temperature to 1673 K. The density and the grain size of the simulated fuel with
the solid solutions used in the measurement were 10.49 g · cm−3 (96.9% of theoretical density) at room temperature and 9.5 μm, respectively. The diameter and thickness of the specimens were 10 and 1 mm, respectively. The thermal diffusivity decreased
from 2.108 m2 · s−1 at room temperature to 0.626 m2 · s−1 at 1673 K. The thermal conductivity was calculated by combining the thermal diffusivity with the specific heat and density.
The thermal conductivity of the simulated fuel with the dissolved fission products decreased from 4.973 W · m−1 · K−1 at 300 K to 2.02 W · m−1 · K−1 at 1673 K. The thermal conductivity of the simulated fuel was lower than that of UO2 by 34.36% at 300 K and by 15.05% at 1673 K. The difference in the thermal conductivity between the simulated fuel and UO2 was large at room temperature, and decreased with an increase in temperature.
Paper presented at the Seventeenth European Conference on Thermophysical Properties, September 5–8, 2005, Bratislava, Slovak
Republic. 相似文献
11.
New NASICON type materials of composition, Li3−2x
Al2−x
Sb
x
(PO4)3 (x = 0·6 to 1·4), have been prepared and characterized by powder XRD and IR. D.C. conductivities were measured in the temperature
range 300–573 K by a two-probe method. Impedance studies were carried out in the frequency region 102−106 Hz as a function of temperature (300–573 K). An Arrhenius behaviour is observed for all compositions by d.c. conductivity
and the Cole-Cole plots obtained from impedance data do not show any spikes on the lower frequency side indicating negligible
electrode effects. A maximum conductivity of 4·5 × 10−6 S cm−1 at 573 K was obtained for x = 0·8 of the Li3−2x
Al2−x
Sb
x
(PO4)3 system. 相似文献
12.
High quality heteroepitaxial thin films of ZnO:N were grown by pulsed laser deposition using a two-step growth method and
annealed in situ at different temperatures and ambient conditions. Films were analyzed by X-ray diffraction (XRD), electrical
measurements, and photoluminescence experiments at low temperatures to investigate the effect of nitrogen doping. The XRD
results demonstrate epitaxial growth on the c-sapphire substrates, with average grain size of 57 nm. Photoluminescence spectra
reveals a peak at 3.061 eV (405.1 nm) which is part of the longitudinal-optical-phonon replicas of excitons bound to neutral
acceptors
\textA10 \textX\textA {\text{A}}_{1}^{0} \,{\text{X}}_{\text{A}} at 3.348 eV (370.4 nm), attributed in recent investigations to a newly reported donor–acceptor pair. Electrical resistivity
and Hall effect measurements were performed using standard four point van der Pauw geometry at room temperature. Fresh films
exhibited a resistivity of 3.1 × 10−3 Ω cm, a carrier density of 1.3 × 1019 cm−3, and a mobility of 53 cm2/V s. During approximately 2 weeks the as-deposited films presented a p-type behavior, as shown by the positive sign of the
Hall constant measured. Thereafter, films reverted to n-type. From electrical measurements and photoluminescence spectra,
the acceptor energy was determined to be 150 meV, in close agreement with reported values. These results are consistent with
those presented in the literature for high purity crystals or homoepitaxial thin films, even though samples for the present
study were processed at lower annealing temperature. 相似文献
13.
T. Çolakoğlu M. Parlak 《Journal of Materials Science: Materials in Electronics》2006,17(12):1017-1024
GaSe thin films were deposited by thermal evaporation technique with Cd doping. X-ray diffraction analysis showed that Cd-doped films have polycrystalline structure with the preferred orientation along (008) direction. Temperature dependent electrical conductivity measurements were carried out in the temperature range of 100–400 K along perpendicular and parallel directions to the growth direction for the films exhibiting p-type conduction determined by hot probe technique. The room temperature conductivity values of the films were found to be as 1.5 × 10−8 and 4.9 × 10−12 (Ω cm)−1 due to the measurements along both perpendicular and parallel directions, respectively. The difference in the conductivity values is the indication of electrical anisotropy in the samples. Carrier conduction in the films was provided by the thermionic emission in the high temperature region (310–400 K) with almost the same activation energies in both directions. Space charge limited current analysis at different temperatures reveals the existence of two discrete sets of trap levels for both perpendicular and parallel directions. Calculated trap levels and trap concentrations are 99 meV, 3.5 × 1012 cm−3 and 418 meV, 2.2 × 105 cm−3 for perpendicular direction, 58 meV, 2.1 × 1018 cm−3 and 486 meV, 1.4 × 1012 cm−3 for parallel direction. The differences in the values of the trap levels and concentrations for both directions confirm the existence of electrical anisotropy in Cd-doped GaSe thin films, because of the structural anisotropy between and inside the crystallites. 相似文献
14.
W. K. Rhim S. K. Chung A. J. Rulison R. E. Spjut 《International Journal of Thermophysics》1997,18(2):459-469
Several thermophysical properties of molten silicon measured by the high-temperature electrostatic levitator at JPL are presented.
They are density, constant-pressure specific heat capacity, hemispherical total emissivity, and surface tension. Over the
temperature range investigated (1350<T
m<1825 K), the measured liquid density (in g·cm−3) can be expressed by a quadratic function,p(T)=p
m−1.69×10−4(T−T
m)−1.75×10−7(T−T
m)2 withT
m andp
m being 1687 K and 2.56 g·cm−3, respectively. The hemispherical total emissivity of molten silicon at the melting temperature was determined to be 0.18,
and the constant-pressure specific heat was evaluated as a function of temperature. The surface tension (in 10−3 N·m−1) of molten silicon over a similar temperature range can be expressed by σ(T)=875–0.22(T−T
m).
Invited paper presented at the Fourth Asian Thermophysical Properties Conference, September 5–8, 1995, Tokyo, Japan. 相似文献
15.
Photoluminescence (PL) studies on LPE-grown InP layers doped with selenium and having carrier concentrations from 1 × 1018 to 1 × 1020 cm−3 have been reported in this paper. Measurements at 300 and 77 K showed that the band to band recombination peak energy shifts
to values as high as 1·7 eV with increasing doping, the increase being sharp beyond 4 × 1019 cm−3. These results have been explained as being the result of the Burstein shift and the band-gap shrinkage. 相似文献
16.
The oxidation behaviour of Zr-based bulk amorphous alloy Zr65Cu17.5Ni10Al7.5 has been studied in air environment at various temperatures in the temperature range 591–684 K using a thermogravimetric
analyser (TGA). The oxidation kinetics of the alloy in the amorphous phase obeys the parabolic rate law for oxidation in the temperature
range 591–664 K. The values of the activation energy and pre-factor as calculated from the Arrhenius temperature dependence
of the rate constants have been found to be 1.80 eV and 2.12 × 109 g·cm−2·sec−1/2, respectively. 相似文献
17.
P. A. Ivanov K. I. Ignat’ev V. N. Panteleev T. P. Samsonova 《Technical Physics Letters》1997,23(10):798-800
Deep surface states are discovered on the interface between 6H-SiC and its native thermal oxide by analyzing the C-V characteristics of metal-oxide-semiconductor structures measured at a high temperature (600 K). The maximum of the density
of states distributed according to energy (D
tm=2×1012 cm−2· eV−1) is at an energy about 1.2 eV below the bottom of the conduction band of SiC. It is postulated that the states discovered
are similar in nature to the P
b centers observed in the SiO2/Si system.
Pis’ma Zh. Tekh. Fiz. 23, 55–60 (October 26, 1997) 相似文献
18.
S. K. Nandi S. Chatterjee S. K. Samanta P. K. Bose C. K. Maiti 《Bulletin of Materials Science》2003,26(7):693-697
Thin films of silicon dioxide are deposited on ZnO/n-Si substrate at a low temperature using tetra-ethylorthosilicate (TEOS).
The ZnO/n-Si films have been characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The border trap
density (Qbt) and fixed oxide charge density (Qf/q) of the SiO2/ZnO/n-Si films are found to be 3.9 × 1010 cm−2 and 1.048 × 1011 cm−2, respectively. The trapping characteristics and stress induced leakage current (SILC) have also been studied under Fowler-Nordheim
(F-N) constant current stressing. 相似文献
19.
The diffusion of samarium in polycrystalline samarium sulfide with a superstoichiometric composition of Sm1.13S has been studied at T = 1000 and 1100°C. It is concluded that Sm atoms predominantly migrate over the boundaries of monocrystalline domains of
the polycrystalline sample. The diffusion coefficient varies within D ≈ 10−2−10−3 cm2/s. In the temperature dependence of the diffusion coefficient, the diffusion activation energy is evaluated at E ∼ 4.6 eV and the preexponential term at D
0 ≈ 1.8 × 1015 cm2/s. 相似文献
20.
In the present paper, a modified self-flux technique has been successfully employed for the growth of pure and praseodymium
substituted (partially) large single crystals of high temperature superconducting Y1−x
Pr
x
Ba2Cu3O7−δ
(x = 0·0,0·2,0·4). Typical sizes of the platy and bulky crystals of pure YBCO(123) material are ≈ 2 × 2 × 0·1 mm3 and 4 × 1 × 1 mm3, respectively. In case of Pr-substitution, the typical sizes of platy and bulky crystals of Y0·8Pr0·2Ba2Cu3O7−δ
and Y0·6Pr0·4Ba2Cu3O7−δ
materials are ≈ 2 × 3 × 0·1 mm3 and 5 × 1 × 1 mm3 and ≈ 1 × 1·5 × 0·1 mm3 and 7 × 0·2 × 0·1 mm3, respectively. The morphology and growth habit of the as-grown single crystals and the critical transition temperature (T
c) of the oxygenated crystals were found to depend on the Pr-content.
Paper presented at the poster session of MRSI AGM VI, Kharagpur, 1995 相似文献