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1.
Jia Li Michiko Yoshitake Weijie Song 《Journal of Materials Science: Materials in Electronics》2014,25(1):343-348
In this work, Bi3.25La0.75Ti3O12 (BLT) thin films were prepared by sol–gel coatings followed by rapid thermal annealing in Ar or O2 ambient. The correlation among annealing ambient, ferroelectric characteristics and surface chemistry of the BLT thin films were investigated. The BLT thin film annealed in Ar showed weaker crystallization, less dense surface and smaller polarization value than that annealed in O2. After 109 cycles, the remnant polarization of the BLT film annealed in Ar decreased to 83.5 % of the initial value while it remained 89.5 % for the sample annealed in O2. X-ray photoelectron spectroscopy results indicated the inferior fatigue characteristics of the sample annealed in Ar was the comprehensive result of oxygen vacancies vicinity to Bi and Ti ion in the thin film. 相似文献
2.
M. Vishwas K. Narasimha Rao A. R. Phani K. V. Arjuna Gowda R. P. S. Chakradhar 《Journal of Materials Science: Materials in Electronics》2011,22(9):1415-1419
Zinc oxide (ZnO) thin films have been prepared on silicon substrates by sol–gel spin coating technique with spinning speed
of 3,000 rpm. The films were annealed at different temperatures from 200 to 500 °C and found that ZnO films exhibit different
nanostructures at different annealing temperatures. The X-ray diffraction (XRD) results showed that the ZnO films convert
from amorphous to polycrystalline phase after annealing at 400 °C. The metal oxide semiconductor (MOS) capacitors were fabricated
using ZnO films deposited on pre-cleaned silicon (100) substrates and electrical properties such as current versus voltage
(I–V) and capacitance versus voltage (C–V) characteristics were studied. The electrical resistivity decreased with increasing
annealing temperature. The oxide capacitance was measured at different annealing temperatures and different signal frequencies.
The dielectric constant and the loss factor (tanδ) were increased with increase of annealing temperature. 相似文献
3.
Amanpal Singh Dinesh Kumar P. K. Khanna Mukesh Kumar B. Prasad 《Journal of Materials Science: Materials in Electronics》2013,24(11):4607-4613
Zinc oxide thin films have been spun coated on p-Si (100) substrates by sol–gel route. These films were annealed at different annealing temperatures from 300 to 1,000 °C in the oxygen ambient. In this way a suitable annealing temperature window for the sol–gel derived ZnO films exhibiting minimum defects (points and dislocations) and better quality (crystal and optical) was investigated. The structural and optical features of ZnO thin films have been examined by X-ray diffraction, atomic force microscopy, UV–Vis spectroscopy, and photoluminescence spectra. The results revealed that the crystallization in the films initiated at 300 °C, improved further with annealing. All the deposited films exhibited wurtzite phase with c-axis orientations. The variations in the position of characteristic (002) peak, stress, strain and lattice parameters are investigated as a function of annealing temperature. The optical band gap is not significantly affected with annealing as observed by UV–Vis transmission spectroscopy. The Photoluminescence spectra exhibited three luminescence centers. The near band edge esmission was observed in UV region which enhanced with the heat treatment, is an indication of improvement in the optical quality of films. The other two visible emissions are related to native defects in ZnO lattice were appeared only for higher annealing (≥700 °C). 相似文献
4.
Multiferroic BFO/PZT multilayer films were fabricated by spin-coating method on the (1 1 1)Pt/Ti/SiO2/Si substrate alternately using PZT(30/70), PZT(70/30) and BFO alkoxide solutions. The structural and ferroelectric properties were investigated for uncooled infrared detector applications. The coating and heating procedure was repeated six times to form BFO/PZT multilayer films. All films showed the typical XRD patterns of the perovskite polycrystalline structure without presence of the second phase such as Bi2Fe4O3. The thickness of BFO/PZT multilayer film was about 200–220 nm. The ferroelectric properties such as dielectric constant, remnant polarization and pyroelectric coefficient were superior to those of single composition BFO film, and those values for BFO/PZT(70/30) multilayer film were 288, 15.7 μC/cm2 and 9.1 × 10?9 C/cm2 K at room temperature, respectively. Leakage current density of the BFO/PZT(30/70) multilayer film was 3.3 × 10?9 A/cm2 at 150 kV/cm. The figures of merit, FV for the voltage responsivity and FD for the specific detectivity, of the BFO/PZT(70/30) multilayer film were 6.17 × 10?11 Ccm/J and 6.45 × 10?9 Ccm/J, respectively. 相似文献
5.
Changyong Liu Yiping Gong Dongyun Guo Chuanbin Wang Qiang Shen Lianmeng Zhang 《Journal of Materials Science: Materials in Electronics》2012,23(9):1711-1714
The compositionally graded Bi4?xNdxTi3O12 (BNT) thin films were prepared on Pt/Ti/SiO2/Si substrates by sol–gel method. Their microstructure, ferroelectric and dielectric properties were investigated. The single-phase upgraded and downgraded BNT films were obtained with (117) preferred orientation. Compared to the homogeneous BNT films prepared by the same conditions, the remanent polarization (P r) and permittivity (ε r) of compositionally graded BNT films were significantly enhanced. The upgraded BNT film showed larger 2P r (34.9?μC/cm2) and ε r (509), and those of downgraded BNT film were 29.4?μC/cm2 and 505. Bi element in the downgraded BNT film accumulated near the interface of film/Pt bottom electrode, which deteriorated the compositional gradient and resulted in decreasing 2P r and ε r compared to the upgraded BNT film. 相似文献
6.
This investigation deals with the effect of annealing temperature on the structural, topographical and optical properties of Zinc Oxide thin films prepared by sol–gel method. The structural properties were studied using X-ray diffraction and the recorded patterns indicated that all the films had a preferred orientation along (002) plane and the crystallinity along with the grain size were augmented with annealing temperature. The topographical modification of the films due to heat treatment was probed by atomic force microscopy which revealed that annealing roughened the surface of the film. The optical properties were examined by a UV–visible spectrophotometer which exhibited that maximum transmittance reached nearly 90% and it diminished with increasing annealing temperature. 相似文献
7.
Jianjun Li Ping Li Guojun Zhang Jun Yu Jia Li Weiming Yang 《Journal of Materials Science: Materials in Electronics》2011,22(3):299-303
The effect of annealing pressure was investigated for Bi3.25La0.75Ti3O12 (BLT) thin films prepared on Pt/TiO2/SiO2/p-Si(100) substrates by sol?Cgel method. The amorphous films were annealed at 750 °C for 30 min under different oxygen pressures varying from 10?4 to 3 atm. The largest P r of 17.8 ??C/cm2 with the E c of 73.6 kV/cm was obtained for the film annealed under 0.1 atm PO2. Then the structure, crystallization degree, and morphology were characterized by X-ray diffraction (XRD), Raman spectroscopy, and field-emission scanning electron microscope (FSEM) to clarify the effect of annealing pressure on the ferroelectric properties. The XRD and Raman spectroscopy results indicated a clear decreasing of the crystallization degree of the films annealed under 10?4 and 3 atm PO2. FSEM results showed the different growth orientation of grains under different oxygen pressures. This study indicated some important effects of annealing pressure on the physical properties of BLT thin films. 相似文献
8.
Investigations on the optical properties of sol–gel derived lanthanum doped lead titanate thin films
《Thin solid films》2002,402(1-2):90-98
In the present work we studied the optical properties of undoped and La doped lead titanate thin films, and also demonstrated that the optical characterization of thin films can be used as an effective diagnostic tool to assess film quality. The optical properties of Pb1−xLaxTi1−x/4O3 [where x=0 (undoped), 10, 15, 20, 25 and 30 at.%] thin films were investigated using both transmission and reflection spectra in the 200–900-nm wavelength range. The refractive index (n), extinction coefficient (k) and the thickness of the film (df) were determined from the measured transmission spectra. The thickness of the film obtained from the interference fringes in transmission or reflection spectra matched well with those obtained from other methods. The appearance of interference fringes is an indication of the thickness uniformity of the film. The low value of extinction coefficient (in the order of 10−2) as observed in our films is a qualitative indication of excellent surface smoothness of the films. The densities of the films were estimated from their refractive indices using effective medium approximation. The average oscillator strength and its associated wavelength were estimated using a Sellmeier-type dispersion equation. Absorption coefficient (α) and the band-gap energy (Eg) were obtained for undoped and La doped films with varying La concentration. It was found that the refractive index and packing fraction values decrease with La doping. La doping was found to decrease the grain size of the films and increase the density of individual grains. Increased La content led to clustering of smaller grains. The observed variation of band-gap energy with La doping has been correlated to the observed microstructure of these films. 相似文献
9.
《Materials Science & Technology》2013,29(6):799-804
AbstractBoth pure and Mg doped thin films were fabricated by sol–gel dip coating. The films were sintered either at 800 or 1000°C. The average grain size of the films was significantly affected by Mg substitution in the hydroxyapatite (HA) structure and change in the sintering temperature. The grains were considerably larger in the films sintered at higher temperatures. In addition, Mg doped films contained significantly larger grains compared to undoped HA films. Mg doping also caused rodlike grains at 800°C, and led to whitlockite (β-TCP) formation at 1000°C. The ratio of the existing phases was estimated as β-TCP/HA=27 : 73. All the films had rough surfaces with high porosity. It was also observed that undoped films had higher surface roughness than Mg doped ones. 相似文献
10.
Zan Zheng Hongjian Zhao Wenjian Weng Gaorong Han Ning Ma Piyi Du 《Journal of Materials Science: Materials in Electronics》2011,22(4):351-358
(Pb
y
Sr1−y
)Zn
x
Ti1−x
O3−x
thin films were prepared on ITO/glass substrate by sol–gel process using dip-coating method. The phase structure, morphology
and ferroelectric property of the thin film were studied. All the thin films show the typical perovskite phase structure.
Both the crystallinity and c/a ratio of the perovskite phase increases initially and then decreases gradually with doping Zn in the thin film. Ferroelectric
properties of the Zn-doped PST thin films, including ferroelectric hysteresis-loop, remnant polarization and coercive force,
decrease gradually with increasing Zn. And the effect of Zn on ferroelectric properties is more obvious in PST thin film with
high content of Pb than that with low Pb although the high lead thin film exhibits high intrinsic ferroelectric properties. 相似文献
11.
H. L. Dong L. X. Li S. H. Yu Y. X. Jin D. Xu 《Journal of Materials Science: Materials in Electronics》2014,25(11):5119-5129
The Bi3/2MgNb3/2O7 (BMN) thin films were prepared via a modified sol–gel process on glass substrates at various post-annealing temperatures. The crystalline structure, morphology and frequency response have been investigated systematically. The X-ray diffraction results indicated that the BMN thin films had different orientations depending on post-annealing temperature. Thin films annealed above 650 °C presented well crystallized cubic pyrochlore structure with (222) orientation, and (400) preferentially oriented were observed when they were annealed below 600 °C. The surface morphology images of the BMN thin films revealed different grain size and grain size distribution, and the average grain size increased from 28.3 to 37.0 nm as the post-annealing temperature increasing. The low frequency dielectric properties of the BMN thin films were closely correlated with the (222) orientation, which was favorable to enhanced dielectric constant and tunability. The high-frequency optical measurements revealed an average transmittance (T av ) varying between 76.6 and 82.2 % and band gap energy (E g ) ranging from 3.40 to 3.44 as a function of the temperature and the crystallite size. Thin film annealed at 700 °C possessed the best crystallinity and highest (222) orientation, and showed the best electrical properties, with a dielectric constant of 105 at 1 MHz, dielectric tunability of 25.8 %, and an average optical transmittance of 82.2 % in the visible range (400–800 nm), making it promising for optical/electronic tunable devices applications. 相似文献
12.
13.
HUA WANG LI LIU JI-WEN XU CHANG-LAI YUAN LING YANG 《Bulletin of Materials Science》2013,36(3):389-393
[Pb 0·95(La1???y Bi y ) 0·05][Zr0·53Ti0·47]O3 (PLBZT) ferroelectric thin films have been synthesized on indium tin oxide (ITO)-coated glass by sol–gel processing. PLBZT thin films were annealed at a relatively low temperature of 550 °C in oxygen ambient. Effects of Bi doping on structure, dielectric and ferroelectric properties of PLBZT were investigated. Bi doping is useful in crystallization of PLBZT films and promoting grain growth. When the Bi-doping content ${\mathit{y}}$ is not more than 0·4, an obvious improvement in dielectric properties and leakage current of PLBZT was confirmed. However, when the Bi-doping content is more than 0·6, the pyrochlore phase appears and the remnant polarization P r of PLBZT thin films is smaller than that of $\left({Pb}_{{1-x}} {\bf La}_{x}\right)\!\!\left({Zr}_{{1-y}} {Ti}_{y}\right){O}_{3}$ (PLZT) thin films without Bi doping. PLBZT thin films with excessive Bi-doping content are easier to fatigue than PLZT thin films. 相似文献
14.
T. Saidani M. Zaabat M. S. Aida R. Barille M. Rasheed Y. Almohamed 《Journal of Materials Science: Materials in Electronics》2017,28(13):9252-9257
Zinc oxide thin films were deposited by sol gel technique on glass substrates using different precursors (zinc acetate, zinc nitrate and zinc chloride). In the present work we investigate the precursor nature influence on structural, morphological, optical, electrical properties and photocatalytic activity of ZnO thin films. For this purpose we have used X-rays diffraction (XRD), atomic force microscopy (AFM), UV–visible spectroscopy and Hall effect measurements for films characterization. The obtained results indicated that ZnO films properties are strongly influenced by the nature of the used precursor as reactant. Films photocatalytic activity was evaluated by the photo-degradation of methylene blue (MB) dissolved in aqueous solution under UV-A light. The obtained results indicated that ZnO thin films prepared from zinc acetate are more efficient than those prepared from zinc nitrate and zinc chloride. 相似文献
15.
16.
A. Abdolahzadeh Ziabari F. E. Ghodsi 《Journal of Materials Science: Materials in Electronics》2012,23(9):1628-1639
Morphological dependence of the optoelectronic properties of sol–gel derived CdO thin films annealed at different temperatures in air has been studied. After preparing, the films were investigated by studying their structural, morphological, d.c. electrical and optical properties. X-ray diffraction results suggest that the samples are polycrystalline and the crystallinity of them enhanced with annealing temperature. The average grain size is in the range of 12–34?nm. The root mean square roughness of the films was increased from 3.09 to 6.43?nm with annealing temperature. It was observed that the electro-optical characteristics of the films were strongly affected by surface roughness. As morphology and structure changed due to heat treatment, the carrier concentration was varied from 1.13?×?1019 to 3.10?×?1019?cm?3 with annealing temperature and the mobility increased from less than 7 to 44.8?cm2 V?1 s?1. It was found that the transmittance and the band gap decreased as annealing temperature increased. The optical constants of the film were studied and the dispersion of the refractive index was discussed in terms of the Wemple–DiDomenico single oscillator model. The real and imaginary parts of the dielectric constant of the films were also determined. The volume energy loss increases more than the surface energy loss at their particular peaks. 相似文献
17.
《Materials Chemistry and Physics》2013,140(1):365-372
Indium gallium zinc oxide (IGZO) transparent semiconductor thin films were prepared by KrF excimer laser annealing of sol–gel derived precursor films. Each as-coated film was dried at 150 °C in air and then annealed using excimer laser irradiation. The influence of laser irradiation energy density on surface conditions, optical transmittances, and electrical properties of laser annealed IGZO thin films were investigated, and the physical properties of the excimer laser annealed (ELA) and the thermally annealed (TA) thin films were compared. Experimental results showed that two kinds of surface morphology resulted from excimer laser annealing. Irradiation with a lower energy density (≤250 mJ cm−2) produced wavy and irregular surfaces, while irradiation with a higher energy density (≥350 mJ cm−2) produced flat and dense surfaces consisting of uniform nano-sized amorphous particles. The explanation for the differences in surface features and film quality is that using laser irradiation energy to form IGZO thin films improves the film density and removes organic constituents. The dried IGZO sol–gel films irradiated with a laser energy density of 350 mJ/cm2 had the best physical properties of all the ELA IGZO thin films. The mean resistivity of the ELA 350 thin films (4.48 × 103 Ω cm) was lower than that of TA thin films (1.39 × 104 Ω cm), and the average optical transmittance in the visible range (90.2%) of the ELA 350 thin films was slightly higher than that of TA thin films (89.7%). 相似文献
18.
Hua Wang Muhui Xu Jiwen Xu Ling Yang Shangju Zhou 《Journal of Materials Science: Materials in Electronics》2010,21(2):145-148
Transparent conductive multilayer Al-doped ZnO (AZO) films were prepared by the spin-on technique with rapid thermal annealing
process at low temperature. The effects of annealing temperature and thickness on microstructure, growth behavior, electrical
properties and optical properties of AZO films were investigated. It was found that AZO films exhibited stronger preferred
c-axis-orientation, the electrical resistivity decreased as it would be expected with the increase of annealing temperature
from 400 to 500 °C and the increase of the number of layers in the film from 1 to 6, but the electrical resistivity tended
to keep at a certain lowest value of 2.7 × 10−4 Ω cm when the annealing temperature was above 500 °C and the number of layers did not exceed 6. The average optical transmittance
of AZO films was over 90% when number of layers in the film did not exceed 4 and decreased as this number increases, but the
annealing temperature had little effect on the average optical transmittance of AZO films. 相似文献
19.
20.
《Science and Technology of Advanced Materials》2003,4(2):143-148
Eu-doped BaTiO3 thin films with a pseudo-cubic perovskite structure were successfully fabricated on magnesia substrates at low temperature by using a high-concentration sol–gel process, in which the newly developed gel-aging process on substrate was employed. Film microstructure, crystallinity, sintering properties and photoluminescence (PL) were investigated. The xerogel thin films exhibited strong PL associated with Eu3+ ions under ultraviolet excitation at room temperature; the PL was visible to naked eyes. The intensity maximum of PL was reached with doping concentration of about 8 mol%. Sintering above 600 °C caused reduction of europium, resulting in a rapid quenching of Eu3+ emission and enhancement of Eu2+ emission. 相似文献