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1.
P. Kanarjov V. Reedo I. Oja Acik L. Matisen A. Vorobjov V. Kiisk M. Krunks I. Sildos 《Physics of the Solid State》2008,50(9):1727-1730
Luminescent films of TiO2: Sm were prepared by the sol-gel method using the spray pyrolysis technique. Various techniques (including IR absorption,
Raman, AFM, XPS, photoluminescence) were used to characterize the samples. After a thermal treatment up to 750°C, intense
Sm3+ luminescence with a well-resolved fine structure was observed under optical excitation within the fundamental absorption
band of the TiO2 host. After further thermal treatments up to 950°C, the luminescence was quenched, although no anataseto-rutile phase transformation
was observed. This behavior is attributed to nanocrystallinity and segregation of Sm ions in the surface layer.
The text was submitted by the authors in English. 相似文献
2.
Zhisong Xiao Bo Zhou Lu Yan Fang Zhu Feng Zhang Anping Huang 《Physics letters. A》2010,374(10):1297-6523
Tm-Er codoped amorphous aluminum oxide thin films were prepared by pulsed laser deposition. Broadband photoluminescence in the wavelength region of 1400-1700 nm comprised of two emissions at around 1532 and 1620 nm was observed. PL performance was investigated as a function of the substrate-heating temperature. Possible energy transfer processes involved in the heat treatment were discussed and nonradiative decay rates were evaluated, by comparing the inverse of measured lifetimes with the calculated radiative decay rates. Our results suggest that Tm-Er codoped Al2O3 thin film might be potential candidate as broadband light sources and amplifiers. 相似文献
3.
R.J. Deokate 《Applied Surface Science》2008,254(7):2187-2195
The cadmium oxide (CdO) and F:CdO films have been deposited by spray pyrolysis method using cadmium acetate and ammonium fluoride as precursors for Cd and F ions, respectively. The effect of temperature and F doping on the structural, morphological, optical and Hall effect properties of sprayed CdO thin films was investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), optical absorption and electrical measurement techniques. TGA and DTA studies, indicates the formation of CdO by decomposition of cadmium acetate after 250 °C. XRD patterns reveal that samples are polycrystalline with cubic structure and exhibits (2 0 0) preferential orientation. Considerable broading of (2 0 0) peak, simultaneous shifting of corresponding Bragg's angle have been observed with respect to F doping level. SEM and AFM show the heterogeneous distribution of cubical grains all over the substrate, which are randomly distributed. F doping shifts the optical gap along with the increase in the transparency of CdO films. The Hall effect measurement indicates that the resistivity and mobility decrease up to 4% F doping. 相似文献
4.
Gas sensor using gold doped copper oxide nanostructured thin films as modified cladding fiber
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Hussein T. Salloom Rushdi I. Jasim Nadir Fadhil Habubi Sami Salman Chiad M Jadan and Jihad S. Addasi 《中国物理 B》2021,30(6):68505-068505
We investigate the spectral response of nanostructured copper oxides thin film. Gold was doped in two different concentrations (2% and 4%) using the spray method. A novel ammonia gas sensor at various concentrations (0-500 ppm) was fabricated by replacing CuO films with a clad region. In addition, the effect of gold doping on structural, optical, and morphological properties has been demonstrated. The study shows that the spectral intensity increases linearly with ammonia concentration. The 4% Au doped CuO presents higher sensitivity compared with 2% doped and pure copper oxides. Time response characteristics of the sensor are also reported. 相似文献
5.
Georgiana Dascalu Gloria Pompilian Bertrand Chazallon Valentin Nica Ovidiu Florin Caltun Silviu Gurlui Cristian Focsa 《Applied Physics A: Materials Science & Processing》2013,110(4):915-922
CoFe2O4 thin films with preferential texture structure, small grain size, and perpendicular magnetic anisotropy can be obtained by the pulsed laser deposition (PLD) technique. In this work, we studied the influence of the Fe3+ ions substitution by three elements from lanthanide group (Dy, La, and Gd) on the structural properties of the thin films. The samples were deposited by Nd:YAG laser (λ=532 nm, 10 ns) ablation of CoFe1.8RE0.2O4, (RE=Dy, La, Gd) targets at various substrate temperatures ranging from room temperature to 600 °C. The microstructure and chemical composition of the thin films were investigated by Raman spectroscopy, XRD, SEM-EDS, and ToF-SIMS. The XRD patterns and Raman spectra of the thin films indicated the formation of a single spinel structure. Thus, the desired substitution of the iron ions in the spinel lattice with the RE elements was achieved in the thin films, although in the bulk material, their presence determined the formation of a residual phase with a perovskite-type structure. 相似文献
6.
This paper reports the photoluminescence and thermoluminescence properties of gamma ray induced rare earth doped yttrium gadolinium mixed oxide phosphor. The europium (Eu3+) was used as rare earth dopant. The phosphor was prepared by chemical co-precipitation method according to the formula (Y2−x−yGdx) O3: Euy3+ (x=0.5; y=0.05). The photoluminescence emission spectrum of the prepared phosphor shows intense peaks in the red region at 615 nm for 5D0→7F2 transitions and the photoluminescence excitation spectra show a broad band located around 220–270 nm for the emission wavelength fixed at 615 nm. The thermoluminescence studies were carried out after irradiating the phosphor by gamma rays in the dose range from 100 Gy to 1 KGy. In the thermoluminescence glow curves, one single peak was observed at about 300 °C of which the intensity increases linearly in the studied dose range of gamma rays. The glow peak was deconvoluted by GlowFit program and the kinetic parameters associated with the deconvoluted peaks were calculated. The kinetic parameters were also calculated by various glow curve shape and heating rate methods. 相似文献
7.
R. Baghdad B. Kharroubi A. Abdiche M. Bousmaha M.A. Bezzerrouk A. Zeinert M. El Marssi K. Zellama 《Superlattices and Microstructures》2012
Mn-doped ZnO thin films with different percentage of Mn content (0, 1, 3 and 5 at.%) and substrate temperature of 350 °C, were deposited by a simple ultrasonic spray pyrolysis method under atmospheric pressure. We have studied the structural and optical properties by using X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and ultra-violet visible near infrared (UV–Vis-NIR) spectroscopy. The lattice parameters calculated for the Mn-doped ZnO from XRD pattern were found to be slightly larger than those of the undoped ZnO, which indicate substitution of Mn in ZnO lattice. Compared with the Raman spectra for ZnO pure films, the Mn-doping effect on the spectra is revealed by the presence of additional peak around 524 cm−1 due to Mn incorporation. With increasing Mn doping the optical band gap increases indicating the Burstein–Moss effect. 相似文献
8.
R. Reshmi R. Sreeja M. K. Jayaraj J. James M. T. Sebastian 《Applied physics. B, Lasers and optics》2009,96(2-3):433-437
Ba0.7Sr0.3TiO3:Eu ferroelectric films were deposited on quartz substrates by pulsed laser deposition. The linear absorption coefficient and the linear refractive index calculated from the transmission spectrum at 532 nm were found to be 1.67×104 cm?1 and 1.82 respectively. The room temperature photoluminescence shows the characteristic emission of Eu3+ ions. The nonlinear optical properties of the film were investigated by a single beam Z-scan setup. The negative nonlinear refractive index and two photon absorption coefficient was found to be ?1.508×10?6 m2/GW and 240 m/GW respectively. The real and imaginary part of the third order susceptibility of the thin films is 2.58×10?17 m2/V2 and 1.16×10?16 m2/V2 respectively. The BST:Eu thin films show good optical limiting property. 相似文献
9.
In this study, the CuxO and Eu: CuxO thin films were prepared by sol gel spin coating method, which is a cheap and simple method, and coated on glass and n-Si substrates to characterize optical properties and to fabricate heterojunction photodiodes, respectively. The optical properties of CuxO films were examined by UV-VIS spectroscopy and the optical band gap of CuxO thin film increased from 2.02 eV to 2.04 eV with Eu doping. Raman measurements confirmed a single crystal phase of CuO. The I-V characteristics of the fabricated photodiodes were carried out under dark and various light intensities. The photosensitivity (Iphoto/Idark), ideality factor (n), barrier height (ΦB) and series resistance (RS) of diodes were calculated and compared. It was observed that the Eu doping improved the optoelectrical properties of CuxO/n-Si photodiode. In addition, the capacitance behavior of diodes was studied by performing C-V measurement and some diode parameters such as ΦB and depletion width (WD) were obtained by using capacitance data. 相似文献
10.
Yan Guan Dayu Zhou Jin Xu Xiaohua Liu Fei Cao Xianlin Dong Johannes Müller Tony Schenk Uwe Schroeder 《固体物理学:研究快报》2015,9(10):589-593
A wealth of studies have confirmed that the low‐field hysteresis behaviour of ferroelectric bulk ceramics and thin films can be described using Rayleigh relations, and irreversible domain wall motion across the array of pining defects has been commonly accepted as the underlying micro‐mechanism. Recently, HfO2 thin films incorporated with various dopants were reported to show pronounced ferroelectricity, however, their microscopic domain structure remains unclear till now. In this work, the effects of the applied electric field amplitude, frequency and temperature on the sub‐coercive polarization reversal properties were investigated for 10 nm thick Si‐doped HfO2 thin films. The applicability of the Rayleigh law to ultra‐thin ferroelectric films was first confirmed, indicating the existence of a multi‐domain structure. Since the grain size is about 20–30 nm, a direct observation of domain walls within the grains is rather challenging and this indirect method is a feasible approach to resolve the domain structure. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
11.
Doped zinc oxide phosphors were synthesized and excited by high-peak power pulsed UV laser at room temperature as well as at liquid nitrogen temperature. There is considerable decrease in the values of life-time at low temperature (77 K), whereas mixed trend is observed in life-time values with change in concentration of didymium, which indicates the perturbation effect in host material. The increased fluorescence quantum yield, emission efficiency and down-conversion phenomena of these selective radiative transitions, in doped phosphors, make them a very promising material for laser medium, vacuum fluorescent displays, fluorescent lamps, information storage and optoelectronic industry. 相似文献
12.
B. I. Turko V. B. Kapustianyk V. P. Rudyk G. A. Lubochkova B. A. Simkiv 《Journal of Applied Spectroscopy》2006,73(2):222-226
We have studied the temperature variation of the intrinsic absorption edge of thin polycrystalline films of zinc oxide, obtained
by high-frequency magnetron reactive sputtering. We ha ve observed that the intrinsic absorption edge in such films is described
by a modified Urbach’s rule. We have calculated the effective frequency of phonons taking part in formation of the absorption
edge.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 2, pp. 200–203, March–April, 2006. 相似文献
13.
We report on a comprehensive study of picosecond laser scribing of gallium doped zinc oxide (GZO) thin films deposited on glass substrates using 355 nm, 532 nm and 1064 nm radiation, respectively. In this study, we investigated the influence of front side and rear side irradiation and determined single pulse ablation thresholds for all three wavelengths. Good ablation quality with full electrical isolation, steep groove walls and a smooth groove bottom was achieved by 355 nm rear side processing with a scanning speed of 224 mm/s. Ridges at the groove rims were found to be between 15 nm and 45 nm high. At similar scanning speed, laser scribing using 532 nm and 1064 nm radiation resulted in a lower ablation quality due to a higher roughness of the groove bottoms or higher ridges at the groove rims. 相似文献
14.
A.R. Phani M. PassacantandoS. Santucci 《Journal of Physics and Chemistry of Solids》2002,63(3):383-392
Crack free, dense and transparent CdTiO3 thin films have been prepared by sol-gel technique using titanium butoxide and cadmium acetate. The formation of the CdTiO3 phase started from 500°C annealing temperature onwards. The complete orthorhombic structure of CdTiO3 was formed on Silicon (100) substrate at an annealing temperature of 600°C for 5 h. As the annealing temperature increased from 600 to 700°C, we have observed the cadmium silicate phase at the interface of Si and CdTiO3 phase. Structural, morphological and elemental evolution of these CdTiO3 thin films produced by sol-gel synthesis were characterised by grazing incidence X-ray diffraction (GIXRD), tapping mode atomic force microscopy (TMAFM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) respectively. 相似文献
15.
M.M. El-Nahass Abdul-Basit A. Saleh A.A.A. Darwish M.H. Bahlol 《Optics Communications》2012,285(6):1221-1224
Thin films of InSe were prepared by thermal evaporation technique. The as-deposited films have nano-scale crystalline nature and the annealing enhanced the degree of crystallinity. The optical properties of nanocrystalline thin films of InSe were studied using spectrophotometric measurements of transmittance, T, and reflectance, R, at normal incidence of light in the wavelength range 200–2500 nm. The optical constants (refractive index, n, and absorption index, k) were calculated using a computer program based on Murmann's exact equations. The calculated optical constants are independent of the film thickness. The optical dispersion parameters have been analysed by single oscillator model. The type of transition in InSe films is indirect allowed with a value of energy gap equals to 1.10 eV, which increased to 1.23 eV upon annealing. 相似文献
16.
Raman spectra of polycrystalline CdO-samples with electron-densities between 0.8 × 1019 and 13 × 1019 cm?3 and mobilities between 80 and 250 cm2V?1sec?1 were observed at 300 and 2 K. Two first order Raman peaks are found at 404 and 345 cm?1 while the second order spectrum is interpreted as due to the following processes: 2LO(L) near 970 cm?1, 2LO(X) near 780 cm?1, 2TO(X) or 2TO(L) at 480 cm?1 and TA + TO(X) at 270 cm?1. The 2LO(L)-peak shift to lower energiesand broadens with increasing electron density. This effect cannot be explained by existing theories. 相似文献
17.
Thin films of tantalum oxide (Ta2O5) have been prepared by pulsed laser deposition technique at different substrate temperatures (300-973 K) under vacuum and under oxygen background (pO2 = 2 × 10−3 mbar) conditions. The films are annealed at a temperature of 1173 K. The as-deposited films are amorphous irrespective of the substrate temperature. XRD patterns show that on annealing, the films get crystallized in orthorhombic phase of tantalum pentoxide (β-Ta2O5). The annealed films deposited at substrate temperatures 300 K and 673 K have a preferred orientation along (0 0 1) plane, whereas the films deposited at substrate temperatures above 673 K show a preferred orientation along (2 0 0) crystal plane. The deposited films are characterized using techniques such as grazing incidence X-ray diffraction (GIXRD), atomic force microscopy (AFM), micro-Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy and UV-visible spectroscopy. FTIR and micro-Raman measurements confirm the presence of Ta-O, Ta-O-Ta and O-Ta-O bands in the films. Grain size calculations from X-ray diffraction and AFM show a decrease with increase in substrate temperature. The variation of transmittance and band gap with film growth parameters are also discussed. 相似文献
18.
Cr doped CdO thin films were deposited on glass substrates by reactive DC magnetron sputtering with varying film thickness from 250 to 400 nm. XRD studies reveal that the films exhibit cubic structure with preferred orientation along the (2 0 0) plane. The optical transmittance of the films decreases from 92 to 72%, whereas the optical energy band gap of the films decreased from 2.88 to 2.78 eV with increasing film thickness. The Wemple–DiDomenico single oscillator model has been used to evaluate the optical dispersion parameters such as dispersion energy (Ed), oscillator energy (Eo), static refractive index (no) and high frequency dielectric constant (ε∞). The nonlinear optical parameters such as optical susceptibility (χ(1)), third order nonlinear optical susceptibility (χ(3)) and nonlinear refractive index (n2) of the films were also determined. 相似文献
19.
Nanostructured zinc oxide thin films were prepared by spray pyrolysis technique using Zn(NO3)2·6H2O as the precursor solution. The resulting films were investigated by X-ray diffraction and scanning electron microscopy to know crystal structure, size of crystallites and surface morphology. The films have been found to be polycrystalline zinc oxide, possessing hexagonal wurtzite crystal structure and nanocrystallite with grain size of approximately 30-35 nm. The LPG sensing performance of the films has been investigated at various concentrations of LPG in air at operating temperatures varying from 225 to 400 °C. At 325 °C the maximum responses of 46.3% and 48.9% have been observed, respectively, for concentrations of 0.8 and 1 vol% of LPG in air (1 vol% of LPG in air corresponds to 50% LEL of LPG in air). The recovery time has been found to be less than the response time for all concentrations of LPG. A possible reaction mechanism of LPG sensing has been proposed. 相似文献
20.
Andreas Talkenberger Ionela Vrejoiu Florian Johann Christian Rder Gert Irmer David Rafaja Gerhard Schreiber Jens Kortus Cameliu Himcinschi 《Journal of Raman spectroscopy : JRS》2015,46(12):1245-1254
BiFeO3 epitaxial thin films fabricated by pulsed laser deposition on different scandate substrates were investigated by means of Raman spectroscopy. We observed periodic changes in Raman position, full width at half maximum and intensity for some phonon modes as a function of the azimuthal angle ϕ. Further analysis revealed the possibility to assign the so far controversial discussed Raman modes at low wavenumbers (<250 cm−1) through rotational Raman measurements at different azimuthal angles, which show high sensitivity to the aforementioned parameters. Furthermore, the ferroelectric/ferroelastic domain structure shown by piezo‐response force microscopy investigations of the samples was confirmed. Our results are supported by symmetry‐based calculations including the analysis of Raman scattering geometry as well as the dielectric function of BiFeO3 in the infrared range. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献