共查询到20条相似文献,搜索用时 0 毫秒
1.
Rajarshi Banerjee 《Materials Letters》2007,61(2):609-612
Nanocrystalline thin films of nominal composition Ni-25 at.% Al have been sputter deposited from a target of the intermetallic compound Ni3Al using different sputtering conditions. Increase in the pressure of sputtering gas resulted in a substantial reduction in the grain size of these nanocrystalline films and a consequent enhancement in their hardness. While films deposited onto heated substrates exhibited larger grain sizes as compared to those deposited on unheated substrates at the same sputtering pressure, the hardness of the former films was substantially higher. The reason for this enhanced hardness is the long-range chemical ordering in films deposited on heated substrates and the formation of L12-Ni3Al, the thermodynamically stable phase for this composition. 相似文献
2.
The effects of residual water on the phase formation, composition, and microstructure evolution of magnetron sputter deposited crystalline alumina thin films have been investigated. To mimic different vacuum conditions, depositions have been carried out with varying partial pressures of H2O. Films have been grown both with and without chromia nucleation layers. It is shown that films deposited onto chromia nucleation layers at relatively low temperatures (500 °C) consist of crystalline α-alumina if deposited at a low enough total pressure under ultra high vacuum (UHV) conditions. However, as water was introduced a gradual increase of the γ phase content in the film with increasing film thickness was observed. At the same time, the microstructure changed drastically from a dense columnar structure to a structure with small, equiaxed grains. Based on mass spectrometry measurements and previous ab initio calculations, we suggest that either bombardment of energetic negative (or later neutralized) species being accelerated over the target sheath voltage, adsorbed hydrogen on growth surfaces, or a combination of these effects, is responsible for the change in structure. For films containing the metastable γ phase under UHV conditions, no influence of residual water on the phase content was observed. The amounts of hydrogen incorporated into the films, as determined by elastic recoil detection analysis, were shown to be low. Overall, the results demonstrate that residual water present during film growth drastically affects film properties, also in cases where the hydrogen incorporation is found to be low. 相似文献
3.
All solid-state thin film batteries (TFBs) consisting of amorphous lithium phosphorus oxynitride (LiPON) solid electrolyte, crystalline LiMn2O4 cathode and crystalline SnO2 anode have been fabricated and characterized. All of the thin films are prepared by RF magnetron sputtering. By fabricating under different pressures and applying low temperature post-annealing (200 °C), the performances of the LiPON electrolytes and SnO2/LiPON/LiMn2O4 TFBs are improved. Suitable working pressures results in pinhole-free amorphous LiPON films with smooth surface and dense micro-structure. The TFBs post-annealed at 200 °C show smooth interface contacts between electrode and electrolyte thin films. The low pressure deposited and post-annealed TFBs exhibits lower impedance and higher cycling stability. Initial open-circuit voltage of 3.8 V and initial capacity of 12 μAh/cm2 are obtained. 相似文献
4.
Transparent and conducting thin films of TiO2:Nb were prepared on glass by reactive dc magnetron sputtering in Ar + O2. Post-deposition annealing in vacuum at 450 °C led to good electrical conductivity and optical transparency. The optical properties in the sub-bandgap region were in good agreement with Drude free electron theory, which accounts for intraband absorption. The band gap of the films was found to be in the range of 3.3 to 3.5 eV and signifies the onset of interband absorption. Electrical conductivities in the 10− 3 Ω cm range were obtained both from dc electrical measurements and from analysis of the optical measurements. 相似文献
5.
Rengang Zhang Baoyi WangLong Wei Xin LiQianshan Xu Shunjin PengIbrahim Kurash Haijie Qian 《Vacuum》2012,86(8):1210-1214
ZnS thin films with the hexagonal structure have been produced by sulfurizing sputter deposited Zn in sulfur vapor for 1 h. These films have been analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), synchrotron radiation photoelectron spectroscopy (SR-PES), Auger electron spectroscopy (AES) and UV-VIS transmission spectra. It is found that at the sulfidation temperature (TS) of 400 °C a little and partial Zn can be transformed to ZnS. At TS = 500 °C, the total conversion of Zn in sulfur vapor can take place and form ZnS with a c-axis preferred orientation. The Zn-to-ZnS conversion is kinetically a reactive diffusion process. Also the ZnS thin film has much greater size of grains than the as-deposited Zn film, due to ZnS recrystallization and growth in sulfur vapor. Residual sulfur existing on the surface of ZnS grains leads to the poor optical transparency and great broadening of absorbing edge in the optical transmittance. However, ZnS thin film prepared by gradient sulfidation exhibits the improved optical transmittance, with a band-gap energy of 3.64 eV. 相似文献
6.
Effect of oxygen partial pressure on the structural and optical properties of sputter deposited ZnO nanocrystalline thin films 总被引:1,自引:0,他引:1
We report the influence of deposition parameters such as oxygen partial pressure and overall sputtering pressure on the structural and optical properties of the as-grown ZnO nanocrystalline thin films. The films were prepared by dc magnetron sputtering using Zn metal target under two different argon and oxygen ratios at various sputtering pressures. Microstructure of the films was investigated using X-ray diffraction and scanning electron microscopy. Optical properties of the films were examined using UV-Visible spectrophotometer. The results show that the films deposited at low oxygen partial pressure (10%) contain mixed phase (Zn and ZnO) and are randomly oriented while the films deposited at higher oxygen partial pressure (30%) are single phase (ZnO) and highly oriented along the c-axis. We found that the oxygen partial pressure and the sputtering pressure are complementary to each other. The optical band gap calculated from Tauc's relation and the particle size calculation were in agreement with each other. 相似文献
7.
Amorphous carbon nitride (CNx, x = 0.05) films were reactively sputtered on Si(100) substrate, and the interface structure was studied by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). In cross-sectional TEM a gray interlayer about 5 nm thick between the bulk CNx film and silicon substrate is observed, and the interface is dense. A little Si impurity (< 1 at.%) is revealed in the films deposited for short time (7 s and 17 s) by XPS measurement. The in-depth XPS analyses indicate that there exists an interlayer with Si impurity above, and a sub-surface layer with C and N below the original surface of silicon substrate. The two layers have different chemical composition and bonding state. 相似文献
8.
Majority of the authors report elaboration of iron oxide thin films by reactive magnetron sputtering from an iron target with Ar-O2 gas mixture. Instead of using the reactive sputtering of a metallic target we report here the preparation of Fe1-xO thin films, directly sputtered from a magnetite target in a pure argon gas flow with a bias power applied. This oxide is generally obtained at very low partial oxygen pressure and high temperature. We showed that bias sputtering which can be controlled very easily can lead to reducing conditions during deposition of oxide thin film on simple glass substrates. The proportion of wustite was directly adjusted by modifying the power of the substrate polarization. Atomic force microscopy was used to observe these nanostructured layers. Mössbauer measurements and electrical properties versus bias polarization and annealing temperature are also reported. 相似文献
9.
The electrical and optical properties of undoped ZnO films deposited by electron cyclotron resonance (ECR) plasma sputtering at room temperature were characterized. The lowest resistivity we achieved was 2.6 × 10− 3 Ωcm with optical transmittance at visible wavelengths higher than 85%. The X-ray diffraction (002) peak was weak and the rocking curve was asymmetrical, indicating that oxygen vacancies prevented large crystalline domains from forming. At low argon-sputtering-gas pressure, carrier concentration and Hall mobility increased with increasing argon pressure. When the optimum pressure (40 mPa) was exceeded, however, Hall mobility and optical transmittance were severely reduced, which indicated that excess Zn atoms were populated at the interstitials of the network. Admitting only 0.67 mPa of O2 gas during deposition deteriorated resistivity over 1 MΩcm due to high excitation efficiency in the ECR plasma. Deposition under a higher magnetic field produced lower resistivities. 相似文献
10.
S. Majumder 《Vacuum》2007,81(8):985-996
SnO2/Pd composite films were synthesized by d.c. sputtering of a SnO2 target followed by thermal evaporation of a thin layer of Pd on top of it. This structure, deposited on Si wafer with 300 μm SiO2 on the top, was subjected to rapid thermal annealing at 573 K for 5 min for the incorporation of Pd in SnO2. The films were characterized by microstructural, optical, FTIR and Raman studies. Liquid petroleum gas (LPG) sensing measurements were carried out on these films. Sensitivity of 72% was obtained at an operating temperature of ∼573 K. The response time for these sensors was found to be ∼27 s. Sensitivity was found to increase with grain growth at higher sensing temperatures. It could be observed that the selectivity for LPG is extremely good as compared to that of methane, hydrogen, CO2 and C2H5OH. 相似文献
11.
D. G. Neerinck A. E. M. De Veirman M. H. J. Slangen Th. G. S. M. Rijks J. C. S. Kools 《Thin solid films》1996,280(1-2):136-141
The average grain size and strain in the direction parallel to the surface of thin Ni0.8Fe0.2 and Cu films, sandwiched between Ta layers, have been determined as a function of layer thickness by grazing incidence X-ray diffraction. The in-plane grain size and grain size distribution were also assessed by plan-view transmission electron microscopy. Standard θ-2θ X-ray powder diffraction was used to determine the uniform strain in the direction perpendicular to the surface. Both for Ni0.8Fe0.2 and Cu, an elongation of the lattice parameter perpendicular to the surface and a compression of the lattice parameter in the plane of the film is observed, which decreases with increasing film thickness. Additionally, for Ni0.8Fe0.2 a non-uniform elongation of the perpendicular interactomic distance at the Ta interfaces is deduced by fitting a kinematical model to the θ-2θ diffraction spectrum. This study illustrates the strength and the complementary character of standard powder X-ray diffraction, grazing incidence X-ray diffraction and transmission electron microscopy for the structural analysis of thin metal films. 相似文献
12.
Thin films of Cu2Te were deposited, at room temperature, on glass substrates by magnetron sputtering from independent Cu and Te sources. This work presents the effect of annealing temperature on the optical, structural, and electrical properties of sputtered Cu2Te films. Annealing above 300 °C resulted in stoichiometric and near stoichiometric Cu2Te phases, whereas temperatures above 400 °C yielded films with single Cu2Te phase. In contrast, annealing at temperatures of 250 °C and below resulted in mixed phases of CuTe, Cu7Te5, Cu1.8Te, and Cu2Te. Analyses of transmittance and reflectance measurements for Cu2Te indicate that photon absorption occurs via indirect band transitions for incident photons with energy above the band gap energy and free carrier absorption below the band gap energy. The determined indirect band gap was 0.90 eV and its associated phonon energy was 0.065 eV. Optical phonon scattering was identified as the mechanism through which the momentum is conserved during absorption by free carriers. Electrical measurements show p-type conductivity and highly degenerate semiconducting behavior with a hole carrier concentration p = 5.18 × 1021 cm− 3. 相似文献
13.
T.H. Scabarozi J. Roche S.H. Lim G. Yong M.W. Barsoum S.E. Lofland 《Thin solid films》2009,517(9):2920-2923
We report on the synthesis and characterization of epitaxial c-axis oriented Nb2AlC thin films deposited on c-axis sapphire (Al2O3) substrates by magnetron sputtering. Selected area electron diffraction reveal that independent of substrate temperature or film stoichiometry, there is the growth of a secondary phase not found in bulk, Nb5Al3Cx with a- and c-axis lattice constants of 7.746 Å and 5.246 Å, respectively. Scanning electron micrographs reveal large surface features, many with hexagonal shape and faceted texture. Atomic force microscopy topographical measurements indicate a surface roughness of approximately 15% of the total film thickness. Electrical transport measurements show typical metal-like conduction with a room temperature resistivity of ≈ 0.9 μΩ-m and a residual resistivity ratio of 2.5. A superconducting transition was found at ≈ 440 mK. 相似文献
14.
In this work, transparent titanium dioxide (TiO2) thin films were deposited onto microscope glass slides by means of the d.c. reactive magnetron sputtering method. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), UV-visible spectroscopy (UV) and contact angle analysis using the Owens-Wendt method for the surface energy calculation. The photocatalytic activity of the films was tested by measuring the photodegradation of Rhodamine-B (RhB) dye under radiation of UV light. Iron-doped TiO2 films were also prepared in order to study the Fe-doping effect on TiO2 photocatalytic activity. The influences of different iron concentrations on the contact angle of the series of Fe-doped TiO2 thin films, were investigated. The influences of total sputtering pressures on TiO2 photocatalytic activity were also investigated. It was observed that the photocatalytic activity of the TiO2 thin films was slightly improved by increasing the total sputtering pressure. Moreover, it was also observed that in general, iron-doping was detrimental for photocatalytic activity, nevertheless the films with low iron concentrations showed better photocatalytic activity than those with high iron concentrations. It was found that iron-doping has changed the wettability appetency of TiO2 coated surfaces. 相似文献
15.
16.
NiAlFe thin films were prepared onto sapphire single crystals by physical vapour deposition (PVD) and these were analysed by X-ray photoelectron spectroscopy (XPS) in combination with argon ion etching to determine the composition depth profile and interfacial characteristics of the samples. Non-linear least square fitting (NLLSF) analysis of the data was required due to the conflict of several peaks of interest. XPS depth profiles show that, for non-annealed NiAlFe–Al2O3, the interface is sharp and oxygen diffusion occurs at different annealing temperatures. Ni remains chemically unaffected by the presence of oxygen while the formation of aluminium oxide compounds occur. Two iron species are present in the film thickness where the low binding energy component is attributed to Fe–Fe or Fe–Al interactions and the higher one to the NiAlFe compound. The reduction-dissolution of the sapphire substrate leads to depletion of oxygen in the sapphire surface layer and the formation of alumina at the NiAlFe–Al2O3 interface. Within the film, aluminium and nickel are present as an intermetallic compound. Annealing of the samples induces surface oxidation and the subsequent formation of an Al2O3 layer. This type of interphase morphology should lead to optimal fibre/matrix (F–M) adhesion, and therefore optimal load transfer between the matrix and reinforcement. 相似文献
17.
The influence of electron injection on the electric-pulse-induced resistive switching of perovskite CaCu3Ti4O12 (CCTO) films was studied by current-voltage (I-V) measurements. The electron injection was reduced by annealing the sample in an O2 atmosphere. The switching from the high-resistance state HRS to the low-resistance state LRS by a filamentary mechanism was suppressed when the carrier injection occurs by Poole-Frenkel emission. The interfacial potential barrier plays a crucial role in determining the carrier injection. 相似文献
18.
Sébastien Saitzek Frédéric Guinneton Laurent Sauques Jean-Raymond Gavarri 《Thin solid films》2008,516(6):891-897
Thermochromic VO2 thin films presenting a phase change at Tc = 68 °C and having variable thickness were deposited on silicon substrates (Si-001) by radio-frequency sputtering. These thin films were obtained from optimized reduction of low cost V2O5 targets. Depending on deposition conditions, a non-thermochromic metastable VO2 phase might also be obtained. The thermochromic thin films were characterized by X-ray diffraction, atomic force microscopy, ellipsometry techniques, Fourier transform infrared spectrometry and optical emissivity analyses. In the wavelength range 0.3 to 25 μm, the optical transmittance of the thermochromic films exhibited a large variation between 25 and 100 °C due to the phase transition at Tc: the contrast in transmittance (difference between the transmittance values to 25 °C and 100 °C) first increased with film thickness, then reached a maximum value. A model taking into account the optical properties of both types of VO2 film fully justified such a maximum value. The n and k optical indexes were calculated from transmittance and reflectance spectra. A significant contrast in emissivity due to the phase transition was also observed between 25 and 100 °C. 相似文献
19.
Fe-O thin films with different atomic ratio of iron to oxygen were deposited on glass and thermally oxidized silicon substrates at temperatures of 300, 473 and 593 K, by reactive magnetron sputtering in Ar+O2 atmosphere. The composition and structure of the thin films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and electrical resistivity. It was found from XRD that with increasing the oxygen partial pressure in the working gas, the crystalline structure of the Fe-O films deposited at the substrate temperature of 473 K gradually changed from α-Fe, amorphous Fe-O, Fe3O4, γ-Fe2O3 to Fe21.34O32. The structure and chemical valence of the Fe3O4 films were analyzed by electron microscopy and XPS, respectively. 相似文献
20.
New materials for a transparent conducting oxide film are demonstrated. Highly transparent Zn2In2O5 films with a resistivity of 3.9 × 10−4 Ω cm were prepared on substrates at room temperature using a pseudobinary compound powder target composed of ZnO (50 mol.%) and In2O3 (50 mol.%) by r.f. magnetron sputtering. MgIn2O4---Zn2In2O5 films were prepared using MgIn2O4 targets with a ZnO content of 0–100 wt.%. The resistivity of the deposited films gradually decreased from 2 × 10−3 to 3.9 × 10−4 Ω cm as the Zn/(Mg + Zn) atomic ratio introduced into the films was increased. The greatest transparency was obtained in a MgIn2O4 film. The optical absorption edge of the films decreased as the Zn/(Mg + Zn) atomic ratio was increased, corresponding to the bandgap energy of their materials. It was found that the resistance of the undoped Zn2In2O5 films was more stable than either the undoped MgIn2O4, ZnO or In2O3 films in oxidizing environments at high temperatures. 相似文献