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1.
Transparent zinc oxide (ZnO) thin films were deposited on various substrates using a pulsed laser deposition (PLD) technique. During the PLD, oxygen pressure and substrate temperature were varied in order to find an optimal preparation condition of ZnO for thin film transistor (TFT) application. Dependence of optical, electrical and crystalline properties on the deposition conditions was investigated. The ZnO thin films were then deposited on SiN/c-Si layer structures in order to fabricate a TFT device. The pulsed laser deposited ZnO films showed a remarkable TFT performance: field effect mobility (μFE) of 2.4-12.85 cm2/V s and ratio of on and off current (Ron/off) in 2-6 order range. Influence of ZnO preparation conditions on the resulting TFT performance was discussed. 相似文献
2.
Wu Ting M. Badaye T. Morishita N. Koshizuka S. Tanaka 《Journal of Superconductivity and Novel Magnetism》1996,9(6):637-645
Recently, superconducting Nd1Ba2Cu3Oy (Ndl23) thin films with high superconducting transition temperature (T c) have been successfully fabricated at our institute employing the standard laser ablation method. In this paper, we report the results of surface characterization of the Nd123 thin films using an ultrahigh vacuum scanning tunneling microscope/spectroscopy (UHV-STM/STS) and an atomic force microscope (AFM) system operated in air. Clear spiral pattern is observed on the surfaces of Nd123 thin films by STM and AFM, suggesting that films are formed by two-dimensional island growth mode. Contour plots of the spirals show that the step heights of the spirals are not always the integer or half-integer number of thec-axis parameter of the structure. This implies that the surface natural termination layer of the films may not be unique. This result is supported byI-V STS measurements. The surface morphology of the Nd123 thin films is compared with that of thec-axis-oriented Y1Ba2Cu3Sy thin films. Surface atomic images of the as-prepared Nd123 thin films are obtained employing both STM and AFM. STS measurements show that most of the surfaces are semiconductive. The results of STS measurements together with the fact that we are able to see the surface atomic images using scanning probe microscopes suggest that exposure to air does not cause serious degradation to the as-prepared surfaces of Nd123 thin films. 相似文献
3.
《Materials Letters》2006,60(13-14):1748-1752
We report an electrochemical deposition of ZnO thin films on SnO2:F coated Transparent Conducting Oxide (TCO) glass substrates from a solution of Zn(NO3)2. A Zn rod acted as a sacrificial anode, while the TCO glass was the cathode. No external bias was applied. The deposition of ZnO thin films was pH sensitive and a pH between 5 and 6 was found to be optimum for film deposition. The deposition was carried out at 60 and 80 °C, with stirring of the solution. X-ray diffraction studies revealed that the ZnO films were of hexagonal phase. Scanning electron microscope (SEM) images showed prominent hexagonal micro-grains with vertical columnar growth. Optical absorption spectra yielded an energy band gap around 3.3 to 3.4 eV. A.C. current–voltage (I–V) and capacitance–voltage (C–V) measurements were carried out using colloidal silver paste as one of the contact. It was found that the ZnO film formed a Schottky junction and the TCO/ZnO/Ag system could be used as an electrical switching device. 相似文献
4.
High purity yttrium was ablated by using frequency quadrupled ultra-violet pulses of a Nd:YAG laser (λ = 266 nm, τFWHM = 7 ns) with power density of about 1 GW/cm2. Laser ablation process was studied using in-situ mass spectrometry of the ablated species in combination with ex-situ analyses of both target surface and deposited films. An increase on the Y ablation rate was found at the beginning, followed by a significant drop with increasing of the number of laser pulses per site until it reaches a constant value after 40 pulses per site. Initial topographic changes on the target surface, observed by scanning electron microscope investigations, and plasma shielding effect could be the origin of these changes on the ablation rate. Careful time-integrated and -resolved mass spectrometric studies of the laser ablated material indicate evident hydridation and oxidation processes in gas phase of ablated yttrium. These results clearly suggest that high purity metallic thin films can be deposited only after a deep and prolonged laser cleaning treatment of the target surface. The present parametric studies are aimed and tailored to prepare photocathodes based on Y thin films to be used in RF photoinjectors. 相似文献
5.
Yanqiao Li Yange Zhang Yan Lei Pinjiang Li Huimin Jia Hongwei Hou Zhi Zheng 《Materials Science and Engineering: B》2012,177(20):1764-1768
A facile wet-chemical method to prepare Bi2S3 thin films with flake nanostructures directly on ITO glass substrate is presented in this paper for the first time. The product was characterized by X-ray powder diffractometer (XRD), Raman spectrometer, scanning electron microscope (SEM), and atomic force microscope (AFM). The one-step solvothermal elements treatment on the ITO substrate spare time to form film by spin-coating process and the film could be tightly attached to the ITO electrode. A conjugated polymer, poly 3-hexylthiophene (P3HT), was then spin-coated on the as-prepared Bi2S3 film to form an inorganic-organic hybrid thin film. The photovoltaic performance of the resulting solar cell device was also investigated. 相似文献
6.
H.-U. Habermeier 《Journal of Superconductivity》2000,13(6):871-875
This chapter introduces the use of substrates for high-temperature superconductor (HTSC) thin-film deposition beyond their usual purpose as chemically inert, lattice-matched support for the films. Substrates are used as functional elements in order to controllably modify the growth mode of YBa2Cu3O7–x
thin films in the case of vicinal-cut SrTiO3 single crystals or to locally modify the surface morphology and film/substrate lattice mismatch in the case of ion implanted SrTiO3. Furthermore, the use of biaxial epitaxial strain is briefly reviewed for HTSC thin films, and the application of this concept to tailor the properties of perovskite thin films in general is shown. 相似文献
7.
A. Salem A. E. Al-Salami K. A. Ziq H. Adrian 《Journal of Superconductivity and Novel Magnetism》2011,24(1-2):159-163
Bi2Sr2Ca2Cu3O10+?? HTSC epitaxial thin films with thickness in the order of 6.0?nm were prepared onto (100) aligned SrTiO3 single-crystal substrates by DC sputtering from stoichiometric targets. As-grown samples were characterized by X-ray diffraction, AC-susceptibility and scanning electron microscopy. X-ray diffraction patterns show that all obtained superconducting thin films were c-axis oriented with a Bi-2223 phase. All reflections (except the substrate ones) can be assigned to the (00l) reflections of the film material (h=k=0, l??0), indicating that the films were grown preferentially with the c-axis normal to the film plane. In order to investigate the crystal quality of these Bi-2223 films, the rocking curves of the (0012) peaks were explored by ??-scans. The rocking curve of the (0012) reflection had a full width at half maximum (FWHM) of 0.30??. This demonstrates that our prepared Bi-2223 thin films have good crystalline quality and high degree of c-axis orientation. The grain size has well known important effects in the magnetic, optical, and electrical properties of metals and alloys. High temperature superconducting thin films, obtained in this work, have nanometer grain size. The mean size of the grains of the samples were determined by X-ray diffraction (XRD) and found to be in the order of 34.8?nm. The superconducting transitions temperature of several Bi-2223 samples is about 103?K. Surface morphology of the films and chemical composition were studied using scanning electron microscopy (SEM) and energy dispersive X-ray microanalysis (EDX). 相似文献
8.
The micrometer and sub-micrometer sized particulates present both on the surface and inside of pulsed laser deposited thin films and structures stand for the main drawback of the method in view of technological applications. We applied a two-laser system in order to withdraw the particulates in case of Ta and TaOx thin films. The Ta targets were irradiated by the first UV laser, while the second IR laser was directed parallel to the target surface, aiming to heat and evaporate the particulates. The morphology of the obtained thin films was studied by scanning electron microscopy. For the TaOx films, the ambient gas pressure influences, besides the size and density of particulates, their propagation velocity. This in turn results in the variation of the optimum delay time between the ablating UV and the second IR laser pulse. For the Ta films we found that a threshold fluence of the IR laser pulse exists, above which completely particulate-free films were deposited. 相似文献
9.
B. Prijamboedi S. Kashiwaya 《Journal of Materials Science: Materials in Electronics》2006,17(7):483-488
On the electron-doped superconductor of Nd2−xCexCuO4−y (NCCO) thin film, the presence of non-c-axis oriented grains, which are identified as (110) reflection peak at 2θ = 32.5∘ in the x-ray diffraction (XRD) spectrum is always observed. Meanwhile, high quality thin films without having impurities
are necessary for device applications. We study the growth of NCCO thin film prepared by pulsed laser deposition technique
and found that the volume fraction of (110) oriented grains depends on the laser fluence. With the laser fluence of around
2.2 J/cm2, NCCO thin film, which is free from the presence of non-c-axis oriented grains, could be obtained. The atomic force microscope
images show that with the absence of (110) oriented grain the c-axis oriented grains grow into rectangular shape with a spiral
growth mode. The rocking curve measurement for (004) peak give a full width at half maximum value of 0.12∘, which confirms the superior quality of the film and this film has superconducting critical temperature (Tc) at 21 K with a transition width (ΔTc) of 1 K. 相似文献
10.
Transparent tin-doped cadmium oxide (Sn-CdO) thin films with different Sn concentration were deposited on quartz glass substrates by pulse laser deposition (PLD) at 400 °C. The film’s crystallographic structure, optical and electrical properties were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), UV-VIS spectrophotometer and Hall system. Results show that doping of Sn enhances the film’s [111] preferred orientation and causes slight shift in the (200) Bragg angle towards higher value. The optical band gaps (Eg) of the Sn-doped films were found to increase with the increase of Sn doping concentration. In addition, proper doping of Sn evidently improves the electrical properties of CdO, such as the resistivity of the CdO film with 2.9 at% Sn doping is about one-twelfth of that of the CdO film, while the carrier concentration is about 13 times of that of the undoped. The improvements both in optical and electrical properties endow that the Sn-CdO thin films have potential application as TCO material for different optoelectronic device applications. 相似文献
11.
L A Kotok L A Kvichko V T Zagoskin Yu G Litvinenko E T Moghilko 《Bulletin of Materials Science》1991,14(2):167-171
An improved method for hot pressing of high temperature superconducting (HTSC) powders prepared by conventional solid phase synthesis of the initial BaCO3, CuO and Ln2O3 allows one to obtain HTSC targets and magnetic shields possessing a high degree of homogeneity. By sputtering such targets HTSC films with critical current density of 3.3·106 A/cm2 have been deposited. Shields, prepared according to this method, show a shielding coefficient of 105 andH c of 79 Öe in the constant magnetic field and in the alternating magnetic field the amplitude is 90 Öe in the frequency range of 70–3000 Hz. 相似文献
12.
Q. Simon W. Peng F. Houdonougbo S. Weber V. Madrangeas M. Guilloux-Viry 《Thin solid films》2009,517(20):5940-783
KTa1 − xNbxO3 (KTN) thin films were grown by pulsed laser deposition on sapphire and MgO substrates. Their structural and high frequency dielectric characteristics evidenced the strong influence of the substrate and suggested possible KTN/MgO interdiffusion that could be responsible for the lower dielectric losses obtained on this substrate. Both undoped and 6% MgO-doped KTN thin films were then grown on sapphire. Dielectric measurements performed at 12.5 GHz by a resonant cavity perturbation method evidenced reduction of losses by MgO-doping. Loss tangent (tan δ) was reduced by a factor of 3 in comparison with undoped films grown on sapphire. 相似文献
13.
《Materials Letters》2004,58(27-28):3591-3596
Barium strontium titanate Ba0.5Sr0.5TiO3 (BST) thin films have been deposited on Pt/Ti/SiO2/Si substrates by a pulsed laser deposition method. The low-frequency dielectric responses of the BST films, grown at different substrate temperatures (Ts), were measured as functions of frequency in the frequency range from 1 kHz to 1 MHz. With increase of Ts, the grain size of BST thin films became larger and the crystallinity was greatly improved, and then the dielectric permittivity increased, while the dielectric dispersion rose drastically. The origin of the large dielectric relaxation is believed to result from the aggravation of oxygen diffusion at the BST/Pt interface for the BST thin films grown at comparatively higher temperatures. This concept could be further explained by considering the influence of post-annealing in oxygen ambient on the dielectric properties of BST thin films. Our results reveal that the dielectric properties are strongly dependent on the processing conditions and the microstructure of thin films. 相似文献
14.
Bi2.55La0.45TiNbO9 (BLTN-0.45) thin films with layered aurivillius structure were fabricated on fused silica substrates by pulsed laser deposition technique. Their structure, fundamental optical constants, and nonlinear absorption characteristics have been studied. The film exhibits a high transmittance (> 60%) in visible-infrared region. The optical band gap energy was found to be 3.44 eV. The optical constant and thickness of the films were characterized using spectroscopic ellipsometric (SE) method. The nonlinear optical absorption properties of the films were investigated by the single-beam Z-scan method at a wavelength of 800 nm laser with a duration of 80 fs. We obtained the nonlinear absorption coefficient β = 4.64 × 10− 8 m/W. The results show that the BLTN-0.45 thin film is a promising material for applications in absorbing-type optical device. 相似文献
15.
Wu Ting M. Badaye T. Morishita N. Koshizuka S. Tanaka 《Journal of Superconductivity》1996,9(6):637-645
Recently, superconducting Nd1Ba2Cu3Oy (Ndl23) thin films with high superconducting transition temperature (T
c) have been successfully fabricated at our institute employing the standard laser ablation method. In this paper, we report the results of surface characterization of the Nd123 thin films using an ultrahigh vacuum scanning tunneling microscope/spectroscopy (UHV-STM/STS) and an atomic force microscope (AFM) system operated in air. Clear spiral pattern is observed on the surfaces of Nd123 thin films by STM and AFM, suggesting that films are formed by two-dimensional island growth mode. Contour plots of the spirals show that the step heights of the spirals are not always the integer or half-integer number of thec-axis parameter of the structure. This implies that the surface natural termination layer of the films may not be unique. This result is supported byI-V STS measurements. The surface morphology of the Nd123 thin films is compared with that of thec-axis-oriented Y1Ba2Cu3Sy thin films. Surface atomic images of the as-prepared Nd123 thin films are obtained employing both STM and AFM. STS measurements show that most of the surfaces are semiconductive. The results of STS measurements together with the fact that we are able to see the surface atomic images using scanning probe microscopes suggest that exposure to air does not cause serious degradation to the as-prepared surfaces of Nd123 thin films. 相似文献
16.
Shuntaro Suzuki Tsuneo Suzuki Hisayuki Suematsu Weihua Jiang Kiyoshi Yatsui 《Thin solid films》2004,457(1):139-142
Titanium iron oxide (Ti-Fe-O) thin films have been successfully deposited by pulsed laser deposition (PLD). Experiments were carried out by using some targets. One was a Ti-50 at.% Fe-sintered target, while the others were Ti and Fe plates with various surface area ratio [SR=SFe/(SFe+STi)] from 30 to 70%. The thin films were analyzed by X-ray diffractometry, Rutherford backscattering spectroscopy (RBS) and transmission electron microscopy (TEM). From XRD analysis, the main phase in the thin films deposited at SR=30 and 50% was β-Ti (Fe). By increasing SR to 70%, the main phase of the thin film changed to TiFe. By phase diagram, composition of TiFe must be between Ti-47.5-50.3 at.% Fe at a temperature of 1085 °C. However, the composition of the thin film deposited at SR=70% was found to be Ti0.15Fe0.62O0.23. Thus, the composition of Fe in the thin film was much greater than the solubility limit. This fact suggests two possibilities. One is that the thin films, which we have deposited, were in a metastable state. The other is that metal oxides of amorphous state could be contained in the thin film. 相似文献
17.
《Materials Letters》2004,58(27-28):3597-3600
Highly c-axis-oriented lithium niobate (LiNbO3) thin films have been grown on Si with optimum thickness of the SiO2 buffer layer by pulsed laser deposition technique. The amorphous SiO2 buffer layer was formed on Si (100) wafer by thermal oxidation method. The crystallinity and c-axis orientation of LiNbO3 films were strongly influenced by the thickness of amorphous SiO2 buffer layers. The optimum thickness of the amorphous SiO2 buffer layer was found to be about 230 nm for the growth of highly c-axis-oriented LiNbO3 films. The achieved films have smooth surface and sharp interface. The prism coupler method indicates that the prepared LiNbO3 films have great potential for optical waveguide device. 相似文献
18.
(001) SrRuO3 (SRO), (001) CaRuO3 (CRO) and (205) BaRuO3 (BRO) thin films were epitaxially grown on (001) LaAlO3 substrates by laser ablation, and the effect of lattice matching on the microstructure and electrical conductivity was investigated. (001) SRO and (001) CRO thin films had a terrace with orthogonal step structure, whereas (205) BRO thin film had an orthogonal structure with tetragonal grains. Epitaxial thin films showed metallic conduction, and the (001) CRO thin films exhibited the highest electrical conductivity, i.e. 1.5 × 105 S m− 1, among the (001) SRO, (001) CRO and (205) BRO thin films. The smaller misfit between thin film and substrate could be associated with the higher electrical conductivity. 相似文献
19.
Martin Amberg Alexander Haag Raphael Storchenegger Patrick Rupper Frederike Lehmeier René M Rossi Dirk Hegemann 《Science and Technology of Advanced Materials》2015,16(5)
We report on the optical properties of thin titanium suboxide (TiOx) films for applications in laser transmission welding of polymers. Non-absorbing fibers were coated with TiOx coatings by reactive magnetron sputtering. Plasma process parameters influencing the chemical composition and morphology of the deposited thin films were investigated in order to optimize their absorption properties. Optical absorption spectroscopy showed that the oxygen content of the TiOx coatings is the main parameter influencing the optical absorbance. Overtreatment (high power plasma input) of the fiber surface leads to high surface roughness and loss of mechanical stability of the fiber. The study shows that thin substoichiometric TiOx films enable the welding of very thin polyurethane membranes and polyamide fibers with improved adhesion properties. 相似文献
20.
Vinh Ai Dao 《Thin solid films》2009,517(14):3971-2413
Laser crystallization of amorphous silicon (a-Si), using a fiber laser of λ = 1064 nm wavelength, was investigated. a-Si films with 50 nm thickness deposited on glass were prepared by a plasma enhanced chemical vapor deposition. The infrared fundamental wave (λ = 1064 nm) is not absorbed by amorphous silicon (a-Si) films. Thus, different types of capping layers (a-CeOx, a-SiNx, and a-SiOx) with a desired refractive index, n and thickness, d were deposited on the a-Si surface. Crystallization was a function of laser energy density, and was performed using a fiber laser. The structural properties of the crystallized films were measured via Raman spectra, a scanning electron microscope (SEM), and an atomic force microscope (AFM). The relationship between film transmittance and crystallinity was discussed. As the laser energy density increased from 10-40 W, crystallinity increased from 0-90%. However, the higher laser density adversely affected surface roughness and uniformity of the grain size. We found that favorable crystallization and uniformity could be accomplished at the lower energy density of 30 W with a-SiOx as the capping layer. 相似文献