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1.
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
2.
Iron oxide thin films were prepared by spray pyrolysis technique onto glass substrates from iron chloride solution. They were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and (UV-vis) spectroscopy. The films deposited at Ts ≤ 450 °C were amorphous; while those produced at Tsub = 500 °C were polycrystalline α-Fe2O3 with a preferential orientation along the (1 0 4) direction. By observing scanning electron microscopy (SEM), it was seen that iron oxide films were relatively homogeneous uniform and had a good adherence to the glass substrates. The grain size was found (by RX) between 19 and 25 nm. The composition of these films was examined by X-ray photoelectron spectroscopy and electron probe microanalysis (EPMA). These films exhibited also a transmittance value about 80% in the visible and infrared range. The cyclic voltammetry study showed that the films of Fe2O3 deposited on ITO pre-coated glass substrates were capable of charge insertion/extraction when immersed in an electrolyte of propylene carbonate (PC) with 0.5 M LiCLO4. 相似文献
3.
La-substituted BiFeO3, Bi0.8La0.2FeO3, thin films were fabricated on Pt/Ti/SiO2/Si substrates by pulsed laser deposition. X-ray diffraction and high-resolution transmission electron microscope were used to analyze the structures of the films. The results show the films fabricated under optimized growth condition are (0 1 2) textured. X-ray photoemission spectroscopy results indicate that the oxidation state of Fe ion is Fe3+ in the films without detectable Fe2+. The films show low leakage current and excellent dielectric characters. Multiferroic properties with a remnant ferroelectric polarization of 5.2 μC/cm2 and a remanent magnetization of 0.02 μB/Fe were established. These results have some implications for further research. 相似文献
4.
Complexing agents are often used to improve the quality of electrodeposited alloys. Influence of different complexing agents with hydroxycarboxylic acid group on the electrodeposited Co-Pt-W thin films has been investigated. Cathodic polarization curves show that the polarization behaviors of electroplating bath with different complexing agents are very different. Surface morphology, phase composition and magnetic properties are observed by means of FESEM, XRD and vibrating sample magnetometer (VSM), respectively. It has been found out that, if citrate was used as complexing agent, the Co-Pt-W thin films were homogeneous and the granular crystals with the average grain size of 2 μm have been observed. Co-Pt-W thin films exhibited hexagonal close packed (hcp) lattice and strong perpendicular anisotropic magnetic behavior (Hc⊥ = 215.5 kA/m; Hc∥ = 55.4 kA/m). In the presence of gluconate, needle-like deposits were obtained and a strong face centered cubic (fcc(1 1 1)) texture was measured. The Co-Pt-W thin films showed isotropic magnetic behavior. In the case of tartate and malate, the coexistence of needle-like deposits and cellular deposits appeared. The XRD patterns showed that the mixed fcc and hcp phase formed. Perpendicular anisotropic magnetic behaviors of thin films, from malate or tartate baths, were not obvious. 相似文献
5.
Ramphal Sharma Anil Ghule R. Joshi J.C. Vyas T. Ganesh Wonjoo Lee 《Applied Surface Science》2009,255(18):8158-8163
Nanocrystalline CuIn3Se5 thin films have been grown on ITO glass substrates using chemical ion exchange reactions with CdS, in alkaline medium at pH 11. The as-deposited films were annealed in air at 200 °C for 30 min and characterized using X-ray diffraction (XRD), transmission electron microscopy, energy dispersive X-ray analysis, X-ray photoelectron spectroscopy, and scanning electron microscopy to study the structural, compositional and morphological properties. The XRD patterns reveal the nanoparticles size to be of 18-20 nm diameter, while from the SEM images the nanoparticles size is estimated to be 20-30 nm. It is observed that the annealed films contain nanocrystallites connected with each other through grain boundaries, with grain size of about 100-125 nm and have an overall n-type electrical conductivity and higher photoconductivity. The current-voltage (I-V) characteristics (in dark and light) of these films indicated the formation of a Schottky like junction between the n-CuIn3Se5 (OVC) and CdS/ITO layers. 相似文献
6.
Nanocrystalline SnO2 thin films were deposited by simple and inexpensive chemical route. The films were characterized for their structural, morphological, wettability and electrochemical properties using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy techniques (SEM), transmission electron microscopy (TEM), contact angle measurement, and cyclic voltammetry techniques. The XRD study revealed the deposited films were nanocrystalline with tetragonal rutile structure of SnO2. The FT-IR studies confirmed the formation of SnO2 with the characteristic vibrational mode of Sn-O. The SEM studies showed formation of loosely connected agglomerates with average size of 5-10 nm as observed from TEM studies. The surface wettability showed the hydrophilic nature of SnO2 thin film (water contact angle 9°). The SnO2 showed a maximum specific capacitance of 66 F g−1 in 0.5 Na2SO4 electrolyte at 10 mV s−1 scan rate. 相似文献
7.
Two kinds of spinel LiMn2O4 thin film for lithium ion micro-batteries were successfully prepared on polycrystal Pt substrates by spin coating methods, which were carried out under ultrasonic irradiation (USG) and magnetic stirring (MSG), respectively. The microstructures and electrochemical performance of LiMn2O4 thin films were characterized by thermogravimetry analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), and galvanostatic charge-discharge measurements. It was found that the crystalline structure of USG samples grew better than that of the MSG samples. At the same time, higher discharge capacity and better cycle stability were obtained for the LiMn2O4 thin films of USG at the current density of 50 μAh/cm2 between 3.0 and 4.3 V. The 1st discharge capacity was 57.8 μAh/cm2-μm for USG thin films and 51.7 μAh/cm2-μm for MSG thin films. After 50 cycles, 91.4% and 69% of discharge capacity could be retained respectively, indicating that ultrasonic irradiation condition during spin coating was more suitable for preparing spinel LiMn2O4 thin films with better electrode performance for lithium ion micro-batteries. 相似文献
8.
Hao Wen Zhifu Liu Jiao Wang Qunbao YangYongxiang Li Jerry Yu 《Applied Surface Science》2011,257(23):10084-10088
Nb2O5 nanorod array films were synthesized by a facile hydrothermal process using niobium metal foil and NH4F as precursors. The Nb2O5 nanorods stand on the niobium metal foil substrate and are less than 100 nm in diameter and about 1 μm in length. X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) characterizations indicate that these nanorods have orthorhombic structure and grew longitudinally along 〈0 0 1〉 direction. The nanorod growth mechanism was discussed. Thermal annealing at a temperature below 500 °C did not change the microstructure of nanorods but improve the crystallinity. The Nb2O5 nanorod array films have been tested as cathode material for lithium battery, which showed a good specific capacity up to 380 mAh g−1 even after 50 charge/discharge cycles. 相似文献
9.
Qingquan XiaoQuan Xie Xiangqian ShenJinmin Zhang Zhiqiang YuKejie Zhao 《Applied Surface Science》2011,257(17):7800-7804
Magnesium films of various thicknesses were first deposited on silicon (1 1 1) substrates by magnetron sputtering method and then annealed in annealing furnace filled with argon gas. The effects of the magnesium film thickness and the annealing temperature on the formation of Mg2Si films were investigated by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The Mg2Si thin films thus obtained were found to be polycrystalline and the Mg2Si (2 2 0) orientation is preferred regardless of the magnesium film thickness and annealing temperature. XRD results indicate that high quality magnesium silicide films are produced if the magnesium/silicon samples are annealed at 400 °C for 5 h. Otherwise, the synthesized films annealed at annealing temperatures lower than 350 °C or higher than 450 °C contain magnesium crystallites or magnesium oxide. SEM images have revealed that microstructure grains in the polycrystalline films are about 1-5 μm in dimensions, and the texture of the Mg2Si films becomes denser and more homogeneous as the thickness of the magnesium film increases. 相似文献
10.
B.Y. Man S.C. XuC. Yang M. LiuS.Z. Jiang Y.Y. MaC.S. Chen A.H. LiuX.G. Gao C.C. WangB. Hu 《Applied Surface Science》2011,257(15):6321-6325
Single-phase β-FeSi2 films on silicon (1 0 0) were fabricated by pulse laser deposition. The structure and crystal quality of the samples were characterized by X-ray diffraction and Fourier transform infrared spectroscopy. The field scanning electron microscopy showed that the film thickness increases with the increasing of the laser fluence. Moreover, atomic force microscopy observations revealed the changes of surface properties with different laser fluence. Based upon all experimental results, it is found that 7 J/cm2 is the most favorable for the formation of β-FeSi2 thin films. 相似文献
11.
Shaoxiong Lin 《Applied Surface Science》2010,256(13):4365-10194
In this paper the formation and characterization of the I-III-VI2 semiconductor compound CuInS2 (CIS) on gold substrate at room temperature by electrochemical atomic layer deposition (EC-ALD) method are reported. Optimum deposition potentials for each element are determined using cyclic voltammetry (CV) technique and Amperometric I-t method is used to prepare the semiconductor compound. These thin films were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared spectroscopy (FT-IR). XRD results indicate that the CIS thin films have a (1 1 2) preferred orientation. The XPS analyses of the films reveal that Cu, In and S are present in an atomic ratio of approximately 1:1:2. And their semiconductor band gaps are found to be 1.50 eV by FT-IR. 相似文献
12.
We investigate an environmentally friendly aqueous solution system for rutile TiO2 violet color nanocrystalline thin films growth on ITO substrate at room temperature. Film shows considerable absorption in visible region with excitonic maxima at 434 nm. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), UV-vis, water surface contact angle and energy dispersive X-ray analysis (EDX) techniques in addition to actual photo-image that shows purely rutile phase of TiO2 with violet color, super-hydrophilic and densely packed nanometer-sized spherical grains of approximate diameter 3.15 ± 0.4 nm, characterize the films. Band gap energy of 4.61 eV for direct transition was obtained for the rutile TiO2 films. Film surface shows super-hydrophilic behavior, as exhibited water contact angle was 7°. Strong visible absorption (not due to chlorine) leaves future challenge to use these films in extremely thin absorber (ETA) solar cells. 相似文献
13.
SrAl2O4:Eu2+,Dy3+ thin films were grown on Si (1 0 0) substrates using the pulsed laser deposition (PLD) technique to investigate the effect of vacuum, oxygen (O2) and argon (Ar) deposition atmospheres on the structural, morphological, photoluminescence (PL) and cathodoluminescence (CL) properties of the films. The films were ablated using a 248 nm KrF excimer laser. Atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS) and fluorescence spectrophotometry were used to characterize the thin films. Auger electron spectroscopy (AES) combined with CL spectroscopy were employed for the surface characterization and electron-beam induced degradation of the films. Better PL intensities were obtained from the unannealed films prepared in Ar and O2 atmospheres with respect to those prepared in vacuum. A stable green emission peak at 515 nm, attributed to 4f65d1→4f7 Eu2+ transitions were obtained with less intense peaks at 619 nm, which were attributed to transitions in Eu3+. After annealing the films prepared in vacuum at 800 °C for 2 h, the intensity of the green emission (520 nm) of the thin film increased considerably. The amorphous thin film was crystalline after the annealing process. The CL intensity increased under prolonged electron bombardment during the removal of C due to electron stimulated surface chemical reactions (ESSCRs) on the surface of the SrAl2O4:Eu2+, Dy3+ thin films. The CL stabilized and stayed constant thereafter. 相似文献
14.
G. Moses Jacob 《Applied Surface Science》2008,254(20):6671-6676
Nanostructured manganese dioxide films were obtained by galvanostatic, pulse and reverse pulse electrodeposition from 0.01 to 0.1 M KMnO4 solutions. The deposition yield was investigated by in situ monitoring the deposit mass using a quartz crystal microbalance (QCM). Obtained films were studied by electron microscopy, X-ray diffraction analysis, energy dispersive spectroscopy, thermogravimetric and differential thermal analysis. The QCM and electron microscopy data were utilized for the investigation of deposition kinetics and film formation mechanism. It was shown that the deposition rate and film microstructure could be changed by variation of deposition conditions. The method allowed the fabrication of dense or porous films. The thickness of dense films was limited to ∼0.1 μm due to the insulating properties of manganese dioxide and film cracking, attributed to drying shrinkage. Porous and crack-free 1-2 μm films were obtained using galvanostatic or reverse pulse deposition from 0.02 M KMnO4 solutions. It was shown that film porosity is beneficial for the charge transfer during deposition and crack prevention in thick films. Moreover, porous nanostructured films showed good capacitive behavior for applications in electrochemical supercapacitors. The porous nanostructured films prepared in the reverse pulse regime showed higher specific capacitance (SC) compared to the SC of the galvanostatic films. The highest SC of 279 F/g in a voltage window of 1 V was obtained in 0.1 M Na2SO4 solutions at a scan rate of 2 mV/s. 相似文献
15.
Molybdenum ditelluride, MoTe2, thin films have been prepared on a glass substrate by depositing first a layer of Mo of 1 μm thickness by rf sputtering and then layers of tellurium of 4 μm thickness followed by annealing, in a vacuum sealed Pyrex tube, at 823 K for one hour. The films have been studied by X-ray diffraction, electron microprobe analysis, scanning electron microscopy and for optical and electrical properties. This indicated that the films so prepared are well crystallized and textured with a hexagonal structure similar to 2H-MoS2. However, the film is non stoichiometric due to the presence of small amounts of oxygen. The optical properties are in good agreement with those of single crystals and film deposited by other means. The room temperature conductivity is of the same order of magnitude as that of single crystals. Finally, MoTe2 has been used as a precursor for the growth of MoTe2−xSx films. 相似文献
16.
The article describes the microstructure and morphological properties of microwave dielectric ceramic thin films. These thin films were successfully prepared on SiO2 (1 1 0) single-crystal substrates by radio frequency magnetron-sputtering system. The microstructure and morphology of the thin films were characterized by X-ray diffraction, scanning electron microscopy, atomic force microscopy, and transmission electron microscopy. The results show that the main phase is Ba0.5Sr0.5Nb2O6,which has a tetragonal perovskite structure, a long strip pattern, and uniform crystal-grain size of about 2-3 μm in length when annealed under 1150 °C for 30 min in an O2 atmosphere. These thin films are of excellent crystallization quality, with a polycrystalline and dense structure. 相似文献
17.
Sawanta S. MaliPravin S. Shinde C.A. BettyPopatrao N. Bhosale Won J. LeePramod S. Patil 《Applied Surface Science》2011,257(23):9737-9746
TiO2 thin films with novel nanocoral-like morphology were successfully grown directly onto the glass and conducting fluorine doped tin oxide coated glass substrates via multi-step hydrothermal (MSH) process. Titanium chloroalkoxide [TiCl2 (OEt)2 (HOEt)2)] precursor was used in an aqueous saturated NaCl in presence of 1 mM HCl catalyst and HNO3 peptizer at 120 °C. Reaction time varied from 3 to 12 h. The morphological features and physical properties of TiO2 films were investigated by field emission scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffraction, Fourier transform IR spectroscopy, Fourier transform Raman spectroscopy, room temperature photoluminescence spectroscopy and X-ray photoelectron spectroscopy. The surface morphology revealed the formation of TiO2 corals having nanosized (30-40 nm) polyps. The photoelectrochemical properties of the TiO2 nanocoral electrodes were investigated in 0.1 M NaOH electrolyte under UV illumination. The results presented in this study highlight two major findings: (i) ability to tune the photoelectrochemical response and photoconversion efficiency via controlled thickness of TiO2 nanocorals and (ii) the substantial increase in short circuit photocurrent (Jsc) due to the improved charge transport through TiO2 nanocorals prepared via MSH process. This approach would be quite useful for the fabrication of nanocoral architecture that finds key applications in photocatalysis, dye-sensitized solar cells and hybrid solar cells. 相似文献
18.
Li LiXiaomei Qin Guobing WangLimin Qi Guoping DuZhijuan Hu 《Applied Surface Science》2011,257(18):8006-8012
Anatase TiO2 nanowires with a diameter of 5-10 nm and length of 500 nm to 2 μm have been successfully synthesized by modifying TiO2 nanoparticles (P25) using the microwave heating method. The microwave power, reaction pressure, and reaction time for the synthesis of TiO2 nanowires were 500 W, 0.5-3.0 MPa (corresponding to a temperature range of 175-260), and 40-70 min, respectively. X-ray diffraction (XRD), field-emission scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and the BET techniques were used to investigate the phase structures, morphologies, and specific surface areas of the TiO2 nanowires. The effects of reaction time, pressure, and different post-treatment processes on the microstructures of TiO2 nanowires were discussed. It has been shown that the microwave heating method is efficient in transforming TiO2 nanoparticles to anatase TiO2 nanowires. 相似文献
19.
M. Losurdo M.M. Giangregorio P. Capezzuto R.G. Toro I.L. Fragalà 《Applied Surface Science》2006,253(1):322-327
High-k polycrystalline Pr2O3 and amorphous LaAlO3 oxide thin films deposited on Si(0 0 1) are studied. The microstructure is investigated using X-ray diffraction and scanning electron microscopy. Optical properties are determined in the 0.75-6.5 eV photon energy range using spectroscopic ellipsometry. The polycrystalline Pr2O3 films have an optical gap of 3.86 eV and a dielectric constant of 16-26, which increases with film thickness. Similarly, very thin amorphous LaAlO3 films have the optical gap of 5.8 eV, and a dielectric constant below 14 which also increases with film thickness. The lower dielectric constant compared to crystalline material is an intrinsic characteristic of amorphous films. 相似文献
20.
Highly-oriented CaCu3Ti4O12 (CCTO) thin films deposited directly on SrTiO3 (1 0 0) substrates have been developed successfully using a chemical solution coating method. X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM) were employed to characterize the structure and the morphology. It was observed that the CCTO thin films had the 1 μm × 1 μm domain-like microstructure that consists of compact grains of about 0.1 μm in size. The cross sectional SEM image shows that the CCTO grains grow regularly close to the clear interface between the CCTO film and the SrTiO3 substrate. The result was discussed in terms of lattice mismatch between CCTO and SrTiO3. 相似文献