共查询到20条相似文献,搜索用时 31 毫秒
1.
M.M. El-Nahass M.A.M. Seyam H.E.A. El-Sayed A.M. Abd El-Barry 《Applied Surface Science》2006,252(18):6218-6227
Thin films of samples of the glassy SxSe100−x system with 0 ≤ x ≤ 7.28 have been prepared by thermal evaporation technique at room temperature (300 K). X-ray investigations show that the structure of pure selenium (Se) does change seriously by the addition of small amount of sulphur S ≤7.28%. The lattice parameters were determined as a function of sulphur content. Results of differential thermal analysis (DTA) of the glassy compositions of the system SxSe100−x were discussed. The characteristic temperatures (Tg, Tc and Tm) were evaluated. Dark electrical resistivities, ρ, of SxSe100−x thin films with different thicknesses from 100 to 500 nm, were measured in the temperature range from 300 to 423 K. Two distinct linear parts with different activation energies were observed. The variation of electrical resistivity of examined compositions has been discussed as a function of the film thickness, temperature and the sulphur content. The application of Mott model for the phonon assisted hopping of small polarons gave the same two activation energies obtained from the resistivity temperature calculations. 相似文献
2.
Polycrystalline PbSe1−xTex ingots were prepared by solid-state microwave synthesis. Thin films of PbSe1−xTex were then deposited onto clean glass substrates using vacuum evaporation technique. Their nanostructure morphologies and stoichiometric ratio were examined using scanning electron microscopy (SEM) and energy dispersive X-ray spectra (EDX). X-ray diffraction (XRD) patterns indicated that the lattice constants of PbSe1−xTex powders and thin films increased with the increasing amount of Te. From the electrical property measurements, the thin films were characterized by n-type behavior. 相似文献
3.
Y.M. Zhao J.Y. Zhang K.W. Liu C.X. Shan B. Yao B.H. Li D.Z. Shen 《Applied Surface Science》2007,253(24):9319-9322
We report the growth of cubic MgxZn1−xO alloy thin films on quartz by electron beam evaporation. It can be found that all the samples have sharp absorption edges by the absorption measurements. X-ray diffraction measurements indicate the MgxZn1−xO films are cubic phase with preferred orientation along the (1 1 1) direction. Energy dispersive spectrometry (EDS) demonstrates that the Mg concentration in MgxZn1−xO films is much higher than the ceramic target used, and the composition can be tuned in a small scope by varying the substrate temperature and the beam electric current. The reasons of this phenomenon are also discussed. 相似文献
4.
S.D. Chavhan 《Applied Surface Science》2008,254(15):4539-4545
Herein is a report of a study on a Cd1−xZnxS thin film grown on an ITO substrate using a chemical bath deposition technique. The as-deposited films were annealed in air at 400 °C for 30 min. The composition, surface morphology and structural properties of the as-deposited and annealed Cd1−xZnxS thin films were studied using EDX, SEM and X-ray diffraction techniques. The annealed films have been observed to possess a crystalline nature with a hexagonal structure. The optical absorption spectra were recorded within the range of 350-800 nm. The band gap of the as-deposited thin films varied from 2.46 to 2.62 eV, whereas in the annealed film these varied from 2.42 to 2.59 eV. The decreased band gap of the films after annealing was due to the improved crystalline nature of the material. 相似文献
5.
N. El-Kabany 《Physica B: Condensed Matter》2012,407(5):817-821
Bulk InxSe1−x (with x=5-25 at%) glasses were prepared using the melt-quench technique. Short range order(SRO) was examined by the X-ray diffraction using Cu(kα) radiation in the wave vector interval 0.28≤k≤6.5 A0−1.The SRO parameters have been obtained from the radial distribution function. The inter-atomic distance obtained from the first and second peak are r1=0.263 and r2=0.460 nm, which is equivalent In-Se and Se-Se bond length. The fundamental structural unit for the studied glasses is In2Se3 pyramid. Using the differential scanning calorimetry (DSC), the crystallization mechanism of InxSe1−x chalcogenide glass has been studied. The glass transition activation energy (Eg) is 289±0.3 kj/mol.There is a correlation amongst the glass forming ability, bond strength and the number of lone pair electrons. The utility of the Gibbs-Di Marzio relation was achieved by estimating Tg theoretically. 相似文献
6.
The optical properties of CdxZn1−xS thin films on glass substrate prepared by spray pyrolysis method
A series of CdxZn1−xS thin films have been deposited on glass substrates using spray pyrolysis technique. The crystallinity and microstructure of CdxZn1−xS thin films have been investigated by X-ray diffraction (XRD). Based on the results of Hall measurements, the films obtained were an n-type semiconductor. The X-ray data analysis of CdxZn1−xS thin films showed that the grain size of the CdxZn1−xS increased with increase in Cd composition. It is observed that the band gap increases as the Cd composition decreases. The results also showed a blue shift of absorption edge of optical transmission spectra is increases as Zn ratio increases. The effects of Cd composition on the structural and optical properties of CdxZn1−xS thin films were related to their grain size, stress and carrier concentration. 相似文献
7.
Wenting Xu Hailing TuQinghua Xiao Qing ChangZongfeng Li Dali Liu 《Applied Surface Science》2011,257(22):9260-9263
The Si1−xGex thin layer is fabricated by two-step Ge ion implantation into (0 0 1) silicon. The embedded SiGe nanoclusters are produced in the Si1−xGex layer upon further annealing. The number and size of the nanoclusters changed due to the Ge diffusion during annealing. Micro defects around the nanoclusters are illustrated. It is revealed that the change of Si-Si phonon mode is causing by the nanoclusters and micro defects. 相似文献
8.
Akinori Kan Hirotaka OgawaYuki Inami Tohru Moriyama 《Physica B: Condensed Matter》2011,406(17):3170-3174
Bismuth layer-structured (Bi7−xSrx)(Fe3−xTi3+x)O21 (BSFT) ceramics were synthesized and the ferroelectric properties and crystal structure were investigated. X-ray powder diffraction profiles and refinement of the lattice parameters indicated single phase BSFT was obtained in the composition range 0-1.5. The lattice parameter b of BSFT remained almost constant, while a slight decrease in the lattice parameter a was observed by the Sr and Ti substitution for Bi and Fe, respectively, which indicated an increase in the orthorhombicity. The dependence of the BSFT lattice parameter on temperature implied a phase transition from the orthorhombic to the tetragonal phase, which was in good agreement with the Curie temperature. The remnant polarization Pr, of BSFT was significantly improved by the Sr and Ti substitution for Bi and Fe, and ranged from 9 to 16 μC/cm2, although no remarkable variation in the coercive field Ec was observed. As a result, a well-saturated P-E hysteresis loop of BSFT ceramic was obtained at x=0.5 with a Pr of 30 μC/cm at an applied voltage of 280 kV/cm. 相似文献
9.
M. Abu El-Oyoun 《Physica B: Condensed Matter》2011,406(1):125-133
Differential scanning calorimetry (DSC) technique was used to study the kinetics of amorphous to crystalline transformation for GaxSe100−x glass system (x=0, 2.5 and 5 at%). The kinetic parameters of GaxSe100−x glass system under non-isothermal conditions are analyzed by the model-free and model-fitting models at different constant heating rates (5-50 K/min). A strong heating rate dependence of the effective activation energy of crystallization was observed. The analysis of the present data shows that the effective activation energy of crystallization is not constant but varies with the degree of crystallization and with temperature as well. The crystallization mechanisms examined using the local Avrami exponents indicate that one mechanism (volume nucleation with one-dimensional growth) is responsible for the crystallization process for heating rates 5-50 K/min for Se glass and two mechanisms (volume nucleation with two- and one-dimensional growth) are working simultaneously during the amorphous-crystalline transformation of the Ga2.5Se97.5 and Ga5Se95 glasses (5-50 K/min). The reaction model that may describe crystallization process of all the compositions of GaxSe100−x glass system is Avrami-Erofeev model (g(α)=[−ln(1−α)]1/n) with n=2 for Se glass. While for Ga2.5Se97.5 and Ga5Se95 glasses, the values of n are equal to 3 and 2 for the heating rates 5-20 and 35-50 K/min, respectively. A good agreement between the experimental and the reconstructed (α-T) curves has been achieved. The transformation from amorphous to crystalline phase in GaxSe100−x glass system demonstrates complex multi-step involving several processes. 相似文献
10.
R.L. Hadimani P.A. BartlettY. Melikhov J.E. SnyderD.C. Jiles 《Journal of magnetism and magnetic materials》2011,323(5):532-534
Gd5(SixGe1−x)4, known for its giant magnetocaloric effect, also exhibits a colossal strain of the order of 10,000 ppm for a single crystal near its coupled first-order magnetic-structural phase transition, which occurs near room temperature for the compositions 0.41≤x≤0.575. Such colossal strain can be utilised for both magnetic sensor and actuator applications. In this study, various measurements have been carried out on strain as a function of magnetic field strength and as a function of temperature on single crystal Gd5Si2Ge2 (x=0.5), and polycrystalline Gd5Si1.95Ge2.05 (x=0.487) and Gd5Si2.09Ge1.91 (x=0.52). Additionally a giant magnetostriction/thermally induced strain of the order of 1800 ppm in polycrystalline Gd5Si2.09Ge1.91 was observed at its first order phase transition on varying temperature using a Peltier cell without the use of bulky equipment such as cryostat or superconducting magnet. 相似文献
11.
Feihui Li 《Applied Surface Science》2009,255(7):4225-4231
The electrochemical behaviors of BiIII, TeIV and SbIII single ions and their mixtures were investigated in nitric acid and hydrochloric acid system separately. Based on which, BixSb2−xTey thermoelectric films were prepared by potentiostatic electrodeposition from the solutions with different concentrations of BiIII, TeIV and SbIII in the two acid systems. The morphologies, compositions, structures, Seebeck coefficients and resistivities of the deposited thin films were characterized and compared by ESEM (or FESEM), EDS, XRD, Seebeck coefficient measurement system and four-probe resistivity measuring device respectively. The results show that although BixSb2−xTey thermoelectric thin film which structure is consistent with the standard pattern of Bi0.5Sb1.5Te3 can be gained in both of the two acid solutions by adjusting the deposition potential, their morphologies and thermoelectric properties have big differences in different acid solutions. 相似文献
12.
O. Aissaoui L. Bechiri M. Benabdeslem A. Amara K. Djessas 《Journal of luminescence》2011,131(1):109-113
Polycrystalline CuIn1−xGaxTe2 bulk films were synthesized by reacting, in stoichiometric proportions, high purity Cu, In, Ga and Te in a vacuum sealed quartz ampoule. The phase structure and composition of the bulk films were analysed by X-ray diffraction and energy-dispersive X-ray analysis, respectively. The bulk samples, of p-type conductivity, are found to be near-stoichiometric, polycrystalline, with tetragonal chalcopyrite structure, predominantly oriented along a direction perpendicular to the (1 1 2) plane. Photoluminescence spectra were recorded at 7 K and 700 mW to characterize the defects and the structural quality. The main peak as a function of composition has been studied. 相似文献
13.
The samples of Cu1−xPtxFeO2 (0 ≤ x ≤ 0.05) delafossite have been synthesized by solid-state reaction method to investigate their optical and electrical properties. The properties of electrical resistivity and Seebeck coefficient were measured in the high temperature ranging from 300 to 960 K, and the Hall effect and the optical properties were measured at room temperature. The obtained results of Seebeck showed the samples are p-type conductor. The optical properties at room temperature exhibited the samples are transparent visible light material with optical direct gap 3.45 eV. The low electrical resistivity, hole mobility and carrier density at room temperature displayed value ranging from 0.29 to 0.08 Ω cm, 1.8 to 8.6 cm2/V s and 1.56 × 1018 to 4.04 × 1019 cm−3, respectively. The temperature range for transparent visible light is below 820 K because the direct energy gap contains value above 3.1 eV. Consequently, the Cu1−xPtxFeO2 delafossite enhance performance for materials of p-type transparent conducting oxide (TCO) with low electrical resistivity. 相似文献
14.
Yu-jie Zhang Hong-guo Zhang Hong-wei Zhang Jing-lan Chen Guang-heng Wu 《Journal of magnetism and magnetic materials》2010,322(15):2251-809
A series of rare-earth doped BiFeO3 samples, Bi1−xRxFeO3 (x=0-1, R=La, Nd, Sm, Eu and Tb), were prepared in this work. X-ray diffraction analysis showed that the structure of rare-earth doped BiFeO3 was transformed from rhombohedral lattice to orthorhombic one by increasing x. The lattice constants and unit-cell volume decreased with the increasing of the doping content, while both the Néel temperature and magnetization were enhanced. A magnetic phase transition was observed at about 35 K for BiFeO3. The variation of the magnetization with temperature depended on applied field strength and magnetizing history, which was explained according to the antiferromagnetic exchange interaction between Fe and R sites in Bi1−xRxFeO3(x>0). The magnetocrystalline anisotropy contributed by Fe sublattice gave rise to a large coercivity in BixNd1−xFeO3 with an orthorhombic structure. 相似文献
15.
Chaoquan Hu Liang QiaoHongwei Tian Xianyi Lu Qing Jiang Weitao Zheng 《Physica B: Condensed Matter》2011,406(13):2658-2662
We have deposited germanium carbide (Ge1−xCx) films on Si(1 0 0) substrate via radio-frequency (RF) reactive magnetron sputtering in a CH4/Ar mixture discharge, and explored the effects of carbon content (x) on the chemical bonding and hardness for the obtained films. We find that x significantly influences the chemical bonding, which leads to a pronounced change in the hardness of the film. To reveal the relationship between the chemical bonding and hardness, first-principles calculations have been carried out. It is shown that as x increases from 0 to 0.33, the fraction of sp3 C-Ge bonds in the film increases at the expense of Ge-Ge bonds, which promotes formation of a strong covalently bonded network, and thus enhances the hardness of the film. However, as x further increases from 0.33 to 0.59, the fraction of sp3 C-Ge bonds in the film gradually reduces, while that of sp3 C-H and graphite-like sp2 C-C bonds increases, which damages the compact network structure, resulting in a sharp decrease in the hardness. This investigation suggests that the medium x (0.17<x<0.40) is most favorable to the preparation of hard Ge1−xCx films due to the formation of dominant sp3 C-Ge bonds. 相似文献
16.
A series of ZnO1−xSx alloy films (0 ≤ x ≤ 1) were grown on quartz substrates by radio-frequency (rf) magnetron sputtering of ZnS ceramic target, using oxygen and argon as working gas. X-ray diffraction measurement shows that the ZnO1−xSx films have wurtzite structure with (0 0 2) preferential orientation in O-rich side (0 ≤ x ≤ 0.23) and zinc blende structure with (1 1 1) preferential orientation in S-rich side (0.77 ≤ x ≤ 1). However, when the S content is in the range of 0.23 < x < 0.77, the ZnO1−xSx film consists of two phases of wurtzite and zinc blende or amorphous ZnO1−xSx phase. The band gap energy of the films shows non-linear dependence on the S content, with an optical bowing parameter of about 2.9 eV. The photoluminescence (PL) measurement reveals that the PL spectrum of the wurtzite ZnO1−xSx is dominated by visible band and its PL intensity and intensity ratio of UV to visible band decrease greatly compared with undoped ZnO. All as-grown ZnO1−xSx films behave insulating, but show n-type conductivity for w-ZnO1−xSx and maintain insulating properties for β-ZnO1−xSx after annealed. Mechanisms of effects of S on optical and electrical properties of the ZnO1−xSx alloy are discussed in the present work. 相似文献
17.
N-type Bi2Te2.7Se0.3 thermoelectric thin films with thickness 800 nm have been deposited on glass substrates by flash evaporation method at 473 K. Annealing effects on the thermoelectric properties of Bi2Te2.7Se0.3 thin films were examined in the temperature range 373-573 K. The structures, morphology and chemical composition of the thin films were characterized by X-ray diffraction, field emission scanning electron microscope and energy dispersive X-ray spectroscopy, respectively. Thermoelectric properties of the thin films have been evaluated by measurements of the electrical resistivity and Seebeck coefficient at 300 K. The Hall coefficients were measured at room temperature by the Van der Pauw method. The carrier concentration and mobility were calculated from the Hall coefficient. The films thickness of the annealed samples was measured by ellipsometer. When annealed at 473 K, the electrical resistivity and Seebeck coefficient are 2.7 mΩ cm and −180 μV/K, respectively. The maximum of thermoelectric power factor is enhanced to 12 μW/cm K2. 相似文献
18.
X.R. Zhao W.-Q. Lu Y. Konishi T. Ishibashi Y. Matsumoto T. Hasegawa 《Applied Surface Science》2006,252(7):2628-2633
BixY3−xFe5O12 thin films have been grown on GGG (Gd3Ga5O12) (1 1 1) substrates by the combinatorial composition-spread techniques under substrate temperature (Tsub) ranging from 410 to 700 °C and O2 pressure of 200 mTorr. In order to study the effect of substrates on the deposition of BixY3−xFe5O12 thin films, garnet substrates annealed at 1300 °C for 3 h were also used. Magneto-optical properties were characterized by our home-designed magneto-optical imaging system. From the maps of Faraday rotation angle θF, it was evident that the Faraday effect appears only when Tsub = 430-630 °C. θF reaches to the maximum value (∼6°/μm, λ = 632 nm) at 500 °C, and is proportional to the Bi contents. XRD and EPMA analyses showed that Bi ions are easier to substitute for Y sites and better crystallinity is obtained for annealed substrates than for commercial ones. 相似文献
19.
Da-Yong Jiang Ke-Wei Liu Yan-Min Zhao Bin Yao De-Zhen Shen 《Applied Surface Science》2008,254(7):2146-2149
MgxZn1−xO alloy films were prepared on sapphire substrates using Ar and N2 as the sputtering gases. The effect of the sputtering gas on the structural, optical and electrical properties of the MgxZn1−xO films was studied. By using N2 as the sputtering gas, the MgxZn1−xO film shows p-type conductivity and the band gap is larger than that employing Ar as the sputtering gas. The reason for this phenomenon is thought to be related to the reaction between N-O or N-Zn, and the N-doping. 相似文献
20.
Ternary polycrystalline Zn1−xCdxO semiconductor films with cadmium content x ranging from 0 to 0.23 were obtained on quartz substrate by pulse laser deposited (PLD) technique. X-ray diffraction measurement revealed that all the films were single phase of wurtzite structure grown on c-axis orientation with its c-axis lattice constant increasing as the Cd content x increasing. Atomic force microscopy observation revealed that the grain size of Zn1−xCdxO films decreases continuously as the Cd content x increases. Both photoluminescence and optical measurements showed that the band gap decreases from 3.27 to 2.78 eV with increasing the Cd content x. The increase in Cd content x also leads to the broadening of the emission peak. The resistivity of Zn1−xCdxO films decreases evidently for higher values of Cd content x. The shift of PL emission to visible light as well as the decrease of resistivity makes the Zn1−xCdxO films potential candidate for optoelectronic device. 相似文献