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1.
ZnO thin films have been deposited on GaN and ZnO substrates at substrate temperatures up to 750 °C by radio-frequency sputtering using ZnO ceramic targets in pure argon or in a mixture of argon and oxygen. By optimizing the sputter parameters, such as sputtering power, Ar/O2 sputtering gas ratio and temperature of the substrates high quality films were obtained as judged from the X-ray rocking curve half width and luminescence line width. The crystallinity of the ZnO films increases with increasing substrate temperature. Yet there are distinct differences between films grown on GaN templates and on O- and Zn-polar ZnO substrates. 相似文献
2.
Ahalapitiya H. Jayatissa Kun Guo Tarun Gupta Ambalangodage C. Jayasuriya 《Journal of Materials Science: Materials in Electronics》2009,20(6):577-581
The coating of transparent ZnO films using zinc 2-ethylhexanoate [Zn(OOCH(C2H5)C4H9)2] as a novel metal organic monomer is reported. Zinc 2-ethylhexanoate is liquid at room temperature and can be spin-coated
on a flat substrate without precipitation of ZnO under ambient condition. The spin-coated films were heated at different temperatures
to remove unwanted organic materials from the surface. It was found that transparent ZnO films could be produced on glass
substrates at low heating temperature (~400 °C). The ZnO films produced using the new monomer were free of cracks and defects.
Also the ZnO films produced using the new monomer have excellent optical transmittance, mechanical properties and small surface
roughness. The surface morphology and degree of crystallinity of the films coated by the new monomer were compared with these
properties of ZnO films produced using zinc acetate-based sol–gels. The results clearly indicate that the novel monomer is
a potential precursor for coating transparent ZnO films at low temperatures. 相似文献
3.
Preparation of alumina films by the sol-gel method 总被引:2,自引:0,他引:2
This review describes our study on preparation of alumina films by a sol-gel process and their several applications that have been investigated since 1986. Alumina films were prepared from alkoxide or inorganic salt. Both as-prepared alumina films were transparent in ultraviolet, visible and near infrared regions. The alumina from inorganic salt (inorganic alumina) was structureless even after annealed at 300–700°C in air, while the alumina from alkoxide (alkoxide alumina) was in pseudo-boehmite at an annealing temperature lower than 400°C and was in - or -type at 400–700°C. Both alumina films became opaque after annealed at temperatures above 1000°C. The inorganic alumina film annealed at 800°C showed a gas permeability that was influenced by physico-chemical properties of penetrant and alumina. Composite films of alumina and poly(vinyl alcohol) (PVA) were hydrophilic but insoluble in water, and removal of PVA from the composite films by annealing at 600°C led to formation of transparent alumina films. Such properties enabled us to use a counter diffusion method for fabricating -Fe2O3-doped alumina films. Alumina films doped with organic dyes such as laser dyes, hole-burning dyes and non-linear optical dyes, which were fabricated by gelation of dye-added alumina sol, exhibited laser emission, hole-spectra and second- or third-harmonic generation properties, respectively. Hydrogenation of alkene was catalyzed by Ni nanoparticles doped alumina films that were prepared by gelation of Ni2+ solution-added alumina sol and annealing the Ni2+-doped alumina gel in hydrogen gas. Nonlinear optical properties were observed for alumina films doped with CdS, Au and Ag nanoparticles, which were fabricated by gelation of Cd2+, HAuCl4 and AgNO3 solution-added alumina sols and annealing the Cd2+-doped alumina gel in H2S gas and the Ag+- and Au3+-doped alumina gels in H2 gas. Rare earth metal ion-doped alumina films, which were prepared by gelation of rare earth metal ion solution-added alumina sol and annealed the ion-doped alumina gel, exhibited not only normal luminescence but also up-conversion emission, energy transfer type luminescence and long lasting luminescence. 相似文献
4.
New ternary rare earth borides with composition RTB2 (R = rare earth metal, T = transition metal) have been synthesized from the elements. From X-ray powder diffraction analysis all compounds (CeRuB2, GdRuB2, GdOsB2 and YbOsB2) were found to crystallize with the LuRuB2-type of structure. A limited range of existence was found for CeRuB2 between 800° and 900°C. 相似文献
5.
M. E. Ghazi M. Izadifard F. Esmaili Ghodsi M. Yuonesi 《Journal of Superconductivity and Novel Magnetism》2012,25(1):101-108
In this work, Zn0.97TM0.03O (TM = Mn, Ni) thin films are deposited onto glass substrates by the sol–gel method, and the effects of transition metal
(TM) substitution on the structural, optical, and magnetic properties of these films are investigated. X-ray diffraction patterns
reveal that all the films have Wurtzite structure. Optical transmittance of the films is recorded in the wavelength range
of 200–800 nm, and the band gap of the films is determined. Optical constants of the films are calculated using a pointwise
unconstrained minimization algorithm. Absorption edge of the films show a small shift depending on the dopant elements. Magnetic
analyzing indicates that both Ni-doped and undoped ZnO films are ferromagnetic at room temperature but for Mn-doped films,
paramagnetic contribution is dominated. 相似文献
6.
Lyudmila Nikolaevna Dem’yanets Lyudmila Li Tatiana Uvarova Yurii Mininzon 《Journal of Materials Science》2008,43(7):2143-2148
Zinc oxide ultra-fine crystalline powders and polycrystalline films of high optical quality were synthesized under soft hydrothermal
conditions. The phase composition, crystal morphology, and luminescent properties of submicron ZnO powders and films were
studied depending on synthesis conditions (system composition, precursor kind, solvent type and concentration, temperature).
For the systems containing metallic zinc, the ZnO growth mechanism was suggested. The most intensive UV luminescence and the
highest values of IUV/IVIS were observed for polycrystalline films grown on Zn substrates. Low-threshold UV lasing at room temperature was found for
ZnO-films, grown in hydrothermal systems with hydroxide or halide solutions as solvents, E
th = 1–5 MW/cm2. The lowest threshold was observed on the ZnO films grown using LiOH as a solvent and zinc nitrate as ZnO-precursor. Clear
mode structures with line-width 0.3 nm are characteristic of the lasing spectra. 相似文献
7.
Zn(1 − x)CdxO solid solutions with a composition ranging from pure ZnO up to x = 0.062 have been grown on ZnO and c-plane sapphire substrates by using metal organic chemical vapor deposition. The optical transmission spectra were used to estimate the cadmium mole fraction of the solid solutions. The lattice deformation and morphology of these films were examined in detail using high resolution X-ray diffraction and atomic force microscopy as Cd incorporation and used substrate. Our study reveals significant lattice deformation from x ≥ 0.7%. The atomic force microscopy images show facetted grains for films grown on ZnO substrate but rather round for c-plane sapphire substrate. The grain shape is controlled by the presence of the ionic charges on the polar surface of ZnO which is disturbed by cadmium incorporation and also the employed substrate material. 相似文献
8.
Single crystalline Eu3+/Tb3+-codoped ZnO nanocrystals have been synthesized by using a simple co-precipitation method. Successful doping is realized so that strong green and red luminescence can be efficiently excited by ultraviolet and near ultraviolet radiation, demonstrating an efficient energy transfer from ZnO host to rare earth ions. The energy transfer from the ZnO host to Tb3+ in ZnO: Tb3+ samples and ZnO host to Eu3+ in the ZnO: Eu3+ samples under UV excitation are investigated. It is found that the red 5D0 → 7F2 emission of Eu3+ ions decreases with increasing temperature but the green 5D4 → 7F5 emission of Tb3+ ions increases with increasing temperature, implying a different energy transfer processes in the two samples. Moreover, energy transfer from Tb3+ ions to Eu3+ ions in ZnO nanocrystals is also observed by analyzing luminescence spectra and the decay curves. By adjusting the doping concentration, the Eu3+/Tb3+-codoped ZnO phosphors emit green and red luminescence with chromaticity coordinates near white light region, high color purity and high intensity, indicating that they are promising light-conversion materials and have potential in field emission display devices and liquid crystal display backlights. 相似文献
9.
Photoluminescence (PL) properties of undoped ZnO thin films grown by rf magnetron sputtering on silicon substrates have been
investigated. ZnO/Si substrates are characterized by Rutherford backscattering (RBS), X-ray diffraction (XRD), Fourier transform
infrared (FTIR), and X-ray photoelectron spectroscopy (XPS). ZrO2 thin films have been deposited on ZnO using microwave plasma enhanced chemical vapour deposition at a low temperature (150°C).
Using metal insulator semiconductor (MIS) capacitor structures, the reliability and the leakage current characteristics of
ZrO2 films have been studied both at room and high temperatures. Schottky conduction mechanism is found to dominate the current
conduction at a high temperature. Good electrical and reliability properties suggest the suitability of deposited ZrO2 thin films as an alternative as gate dielectric on ZnO/n-Si heterostructure for future device applications. 相似文献
10.
W.A. Bonner 《Materials Research Bulletin》1977,12(3):289-298
A flux composed of lithium and rare earth molybdates has been found to be an effective transfer medium for the preparation of yttrium and rare earth iron gallium and aluminum garnets. Magnetic bubble domain properties of epitaxial iron garnet films grown from the molybdate flux are easily controlled by virtue of the transfer process including dimensional control for submicron thick films. The properties of these films compare well to those grown from the PbO·B2O3 flux, but the films are contaminant free. This is particularly important for the growth of Nd-doped YAG laser films. Stability region of the garnet phase in the Li2MoO4Y2O3MoO3 pseudo-ternary system and solubility are discussed as related to crystal and film growth. 相似文献
11.
Highly conductive and transparent films of Ga-doped ZnO (GZO) have been prepared by pulsed laser deposition using a ZnO target with Ga2O3 dopant of 3 wt.% in content added. Films with resistivity as low as 3.3 × 10− 4 Ω cm and transmittance above 80% at the wavelength between 400 and 800 nm can be produced on glass substrate at room temperature. It is shown that a stable resistivity for use in oxidation ambient at high temperature can be attained for the films. The electrical and optical properties, as well as the thermal stability of resistivity, of GZO films were comparable to those of undoped ZnO films. 相似文献
12.
Sheo K. Mishra Rajneesh K. Srivastava S. G. Prakash 《Journal of Materials Science: Materials in Electronics》2013,24(1):125-134
In the present work, the effect of annealing temperature on the luminescence and photoconductivity properties of ZnO nanoparticles (NPs) has been investigated. The ZnO NPs have been prepared at low temperature by a simple one step solid state reaction method using ZnSO4·7H2O as a starting precursor. X-ray diffraction results show, the prepared samples have a hexagonal wurtzite structure of ZnO NPs. FE-SEM reveals that the prepared ZnO nanoparticles have perfect spherical shape with little agglomeration. UV–visible absorption spectrum of as-prepared ZnO sample shows an absorbance peak at ~372 nm (~3.32 eV), which is blue shifted as compared to bulk ZnO (~386 nm). The annealed sample exhibits red shift of absorption peak. The photoluminescence spectra of as-prepared sample as well as annealed samples show one emission peak in UV region, and violet, blue, blue-green and green emissions in visible region. The sample annealed at 650 °C results in a significant reduction in luminescence as compared to that of the sample annealed at 450 °C. The photoconductivity properties such as voltage dependence of photocurrent, growth and decay of photocurrent as well as wavelength dependence of photocurrent have been studied in detail. 相似文献
13.
Liang Zhang Song-bai Xue Li-li Gao Yan Chen Sheng-lin Yu Zhong Sheng Guang Zeng 《Journal of Materials Science: Materials in Electronics》2009,20(12):1193-1199
Ternary lead free solder alloys Sn–Ag–Cu were considered as the promising alternatives to conventional SnPb alloys comparing with other solders. In the present work, effects of trace amounts of rare earth Ce on the wettability, mechanical properties and microstructure of Sn–Ag–Cu solder have been investigated by means of scanning electron microscopy and energy dispersive X-ray analysis systematically. The results indicate that adding trace amount of rare earth Ce can remarkably improve the wettability, mechanical strength of Sn–Ag–Cu solder joint at different temperature, especially when the content of rare earth Ce is at about 0.03%, the tensile strength will be 110% times or more than that of the lead free solder joint without rare earth Ce addition. Moreover, it was observed that the trace amount of rare earth Ce in Sn–Ag–Cu solder may refine the joint matrix microstructure, modify the Cu6Sn5 intermetallic phase at the copper substrate/solder interface, and the intermetallic compound layer thickness was reduced significantly. In addition, since rare earth Ce possesses a higher affinity to Sn in the alloy, adding of rare earth Ce can also lead to the delayed formation and growth of the intermetallic compounds of Ag3Sn and Cu6Sn5 in the alloy. 相似文献
14.
Calcium fluoride (CaF2) and the rare earth doped CaF2 films have been electrodeposited on indium tin oxide (ITO) electrode through electrochemical generation of acid in aqueous solutions near room temperature. For CaF2 film electrodeposition, the local pH at ITO surface is lowered by the electrochemical oxidation of ascorbate anion, and then the Ca-ethylene diamine tetraacetic acid disodium complexes which are close to the ITO electrode are decomposed to release free Ca2+ to react with F−to form CaF2 deposit onto ITO. In the same way, RE-doped CaF2 films have been electrodeposited onto ITO electrode. The morphology of films studied by scanning electron microscopy revealed that they are agglomerated and dense. The films showed a little [111] preferred orientation by X-ray diffraction. It was also proved that doped RE ions were distributed homogeneously in the film by energy dispersive spectroscopy mapping. The optical properties of the electrodeposited CaF2, CaF2:Eu and CaF2:Tb films were studied by photoluminescence, and all films exhibit intense emission peaks. 相似文献
15.
M. Pelizzone A. Treyvaud P. Spitzli Ø. Fischer 《Journal of Low Temperature Physics》1977,29(5-6):453-465
We have studied the susceptibility of all (RE)
x
Mo6S8 compounds between 1.3 and 300 K (RE = rare earth). In the two superconducting compounds Ho
1.2
Mo
6
S
8
and Dy
1.2
Mo6S8 magnetic ordering is expected in the temperature range 0.1–1 K. The magnetic transition in CeMo6S8 at2.25 K is of antiferromagnetic nature. A second anomaly at 1.6 K in this compound may announce a low-temperature ferromagnetic state. 相似文献
16.
Thin polycrystalline ZnO films were obtained by thermal oxidation of metallic Zn films, thermally deposited on various substrates, such as silica, sapphire and glass, in both air and pure oxygen atmospheres. The quality of the ZnO layers was asserted by Hall effect, cathodoluminescence and atomic force microscopy measurements. Electron concentration of 7.32×1012 cm−3 and mobility of 14.2 cm2/V s with root mean square roughness of 30 nm were obtained for the 900 °C annealed ZnO films in oxygen. Room temperature cathodoluminescence spectra consisted of a narrow near band edge luminescence band and a broad defect-related green band with peak positions at 380 and 500 nm, respectively. ZnO film luminescence properties improved dramatically with the increase of annealing temperature and decrease of O2 pressure. 相似文献
17.
K. V. Mahesh S. Anas S. Rahul S. Ananthakumar 《Journal of Materials Science: Materials in Electronics》2013,24(5):1495-1504
Nano size ZnO–Bi2O3 varistor precursor powders containing Y2O3 and Pr6O11 rare earth dopants were prepared by low temperature refluxing at 80 °C. Effect of rare earth dopants, densification by two-step sintering, evolution of microstructures and their influence on varistor properties were investigated. Chemically synthesized nano- precursor varistor powders produced controlled grain size in two-step sintering in which the average sintered ZnO grain size was reduced to at least half compared to the conventionally processed ZnO–Bi2O3 varistors. The study revealed that such grain size reduction is highly beneficial to attain enhanced varistor properties. 相似文献
18.
Tao Lin Xiao-wei Zhang Yun-ji Wang Jun Xu Neng Wan Jian-feng Liu Ling Xu Kun-ji Chen 《Thin solid films》2012,520(17):5815-5819
SiO2 thin films co-doped with ZnO nanoparticles and Eu3 + ions were prepared by sol-gel method. The formation of nano-sized ZnO particles was confirmed by X-ray diffraction patterns and transmission electron microscopy. The characteristic emission bands from Eu3 + ions can be observed at room temperature and the luminescence intensity is increased obviously by introducing ZnO nanoparticles into Eu3 +-doped silica films. The integrated luminescence intensity is influenced by the concentration and size of ZnO particles, suggesting effective energy transfer from nano-sized ZnO to Eu3 + ions. It is argued that the efficient luminescence enhancement occurs under the suitable Zn2 + amount and annealing temperature. 相似文献
19.
Single crystalline undoped and Ga-doped n-type zinc oxide (ZnO) films were grown on sapphire (Al2O3) substrates by inductively coupled plasma (ICP) metal organic chemical vapor deposition. Effects of growth variables on the structural, optical, and electrical properties of ZnO films have been studied in detail. Single crystal films with flat and smooth surfaces were reproducibly obtained, with application of sample bias and O2 ICP. The best film properties were obtained at the growth condition of 650 °C, 400 W ICP power, − 94 V bias voltage, O/Zn (VI/II) ratio of 75. Single crystalline Ga doped n-ZnO films were also obtained, with free carrier concentration of about 1.5 × 1019/cm3 at 1 at.% Ga concentration. 相似文献
20.
Gurmeet Singh Lotey N. K. Verma 《Journal of Materials Science: Materials in Electronics》2013,24(10):3723-3729
Pure and rare earth metal ions (Gd3+, Tb3+, Dy3+)-doped BiFeO3 nanoparticles have been synthesized by the sol–gel method. The effect of doping of rare earth metal ions on structural, magnetic, dielectric and magnetodielectric properties of synthesized nanoparticles have been investigated. Synthesized nanoparticles have been found to be possessing spherical morphology, with average particle size, 25–46 nm. Structural study confirms that 15 % mole fraction doping of the rare earth metal ions results in structural transformation from rhombohedral to orthorhombic phase. Magnetic study reveals that the synthesized nanoparticles exhibit well saturated ferromagnetic magnetic loops. Dielectric measurements show that doping of rare earth metal ions results in high dielectric constant as compared to that of pure BiFeO3. Magnetoelectric coupling in the synthesized nanoparticles, established by performing magnetodielectric measurements, reveals that the doped nanoparticles exhibit high magnetodielectric coefficient as compared to its pure form. The high value of saturation magnetization, 5.22 emu/g, dielectric constant, 900 and magnetodielectric coefficient, 5.82 %, have been observed in Dy-doped BiFeO3 nanoparticles. The observed trend in the properties of the synthesized nanoparticles has been explained on the basis of doping as well as size of the synthesized nanoparticles. 相似文献