共查询到20条相似文献,搜索用时 31 毫秒
1.
M.G. El-Shaarawy 《Journal of Physics and Chemistry of Solids》2005,66(7):1247-1251
The electrical properties of the solid electrolytes Ag7I4VO4-Al2O3 (0-40 mol% Al2O3) are investigated. The electrical conductivity, dielectric constant and dielectric loss are increased by increasing the concentration of Al2O3; showing a maximum at 30 mol% Al2O3. The conductivity is found to be increased by decreasing the particle size of Al2O3. The results are explained using the random resistor network model (RRN). This is due to the formation of a highly conducting interface layer along the matrix-particle interface. This layer is destroyed at concentrations higher than 30 mol% Al2O3. 相似文献
2.
Sandwich-structure Al2O3/HfO2/Al2O3 gate dielectric films were grown on ultra-thin silicon-on-insulator (SOI) substrates by vacuum electron beam evaporation (EB-PVD) method. AFM and TEM observations showed that the films remained amorphous even after post-annealing treatment at 950 °C with smooth surface and clean silicon interface. EDX- and XPS-analysis results revealed no silicate or silicide at the silicon interface. The equivalent oxide thickness was 3 nm and the dielectric constant was around 7.2, as determined by electrical measurements. A fixed charge density of 3 × 1010 cm−2 and a leakage current of 5 × 10−7A/cm2 at 2 V gate bias were achieved for Au/gate stack /Si/SiO2/Si/Au MIS capacitors. Post-annealing treatment was found to effectively reduce trap density, but increase in annealing temperature did not made any significant difference in the electrical performance. 相似文献
3.
H. Wang 《Journal of luminescence》2009,129(2):110-113
Enhanced photoluminescence (PL) mechanism of Er3+-doped Al2O3 powders by Y3+ codoping at wavelength 1.53 μm has been investigated through PL measurements of 0.1 mol% Er3+- and 0-20 mol% Y3+-codoped Al2O3 powders prepared at a sintering temperature of 900 °C in a non-aqueous sol-gel method. PL intensity and lifetime of Er3+-Y3+-codoped Al2O3 powders composed of γ-(Al,Er,Y)2O3 and θ-(Al,Er,Y)2O3 phases increased with increasing Y3+-codoping concentration. The 10-20 mol% Y3+ codoping in 0.1 mol% Er3+-doped Al2O3 powders intensified the PL intensity by about 20 times, with a PL lifetime prolonged from 3.5 to 5.8 ms. A maximal increase of the optical activity of Er3+ in 0.1 mol% Er3+-Y3+-codoped Al2O3 powders about one order was achieved by 10-20 mol% Y3+ codoping. It is found that the improved PL properties for Er3+-Y3+-codoped Al2O3 powders are mainly attributed to enhanced optical activation of Er3+ in the Al2O3 by Y3+ codoping, and to the slightly increased radiative quantum efficiency of Er3+ in the Al2O3. 相似文献
4.
The 1 mol% Er3+- and 0-20 mol% Yb3+-codoped Al2O3 powders have been prepared by the nonaqueous sol-gel process using aluminum isopropoxide as precursor, acetylacetone as chelating agent, nitric acid as catalyzer, and hydrated erbium and ytterbium nitrate as dopant under isopropanol environment. The two crystalline types of doped Al2O3, γ and θ, and a stoichiometric compound, (Yb,Er)3Al5O12, were obtained for all the Er3+-Yb3+-codoped Al2O3 powders at the sintering temperature of 1000 °C. The maximal intensity of both the green and red up-conversion emissions centered at about 523, 545, and 660 nm was observed for the 1 mol% Er3+- and 10 mol% Yb3+-codoped Al2O3 powders. The intensity ratio of the red to green up-conversion emission (Ired/Igreen) increased with increasing the Yb3+ doping concentration for the Er3+-Yb3+-codoped Al2O3 powders. Furthermore, the intensity ratio of the green up-conversion emission at about 523 to 545 nm (I523/I545) was proportional to the Yb3+ doping concentration and pump electric current, which was associated with the elevated temperature of powders. 相似文献
5.
A series of Er3+/Yb3+-co-doped 60Bi2O3-(40−x) B2O3 -xGa2O3 (BBGA x=0, 4, 8, 12, 16 mol%) glasses have been prepared. The absorption spectra, emission spectra, fluorescence lifetime of Er3+:4I13/2 level and thermal stability were measured and investigated. Three Judd-Ofelt intensity parameters Ωt (t=2,4,6) (Ω2=(4.67-5.93)×10−20 cm2, Ω4=(1.50-1.81)×10−20 cm2, Ω6=(0.92-1.17)×10−20 cm2) of Er3+ ions were calculated by Judd-Ofelt theory. It is found that the Ω6 first increases with the increase of Ga2O3 content from 0 to 8 mol% and then decreases, which is mainly affected by the number of non-bridging oxygen ions of the glass network. The high peak of stimulated emission cross-section () of Er3+: 4I13/2→4I15/2 transition were obtained according to McCumber theory and broad full width at half maximum (FWHM=69-76 nm) of the 4I13/2→4I15/2 transition of Er3+ ions were measured. The results indicate that these new BBGA glasses can be used as a candidate host material for potential broadband optical amplifiers. 相似文献
6.
Choon-Woo Nahm 《Solid State Communications》2003,127(5):389-393
The nonlinear electrical properties and stability against DC accelerated aging stress of various varistors, which are composed of ZnO-Pr6O11-CoO-Cr2O3-Dy2O3 (ZPCCD)-based ceramics, was investigated as a function of Dy2O3 content. The varistors with Dy2O3 exhibited a high nonlinear exponent above 30, compared with that without Dy2O3. The varistor with 0.5 mol% Dy2O3 exhibited the highest nonlinearity, with a nonlinear exponent of 66.6 and a leakage current of 1.2 μA. Furthermore, this varistor showed the high stability, in which the variation rate of varistor voltage, of nonlinear exponent, and of leakage are −1.9, −10.5, and +275.0%, respectively, under DC accelerated aging stress, 0.95 V1 mA/150 °C/24 h. 相似文献
7.
This paper reports the spectral properties of Nd3+:Ca2Nb2O7. The spectral parameters of Nd3+ in Nd3+:Ca2Nb2O7 crystal have been investigated based on Judd-Ofelt theory. The spectral parameters were obtained. The parameters of line strengths Ωλ are Ω2=4.967×10−20 cm2, Ω4=5.431×10−20 cm2, Ω6=5.693×10−20 cm2. The radiative lifetime, the fluorescence lifetime and the quantum efficiency are 122 μs, 103 μs and 84.4%, respectively. The fluorescence branch ratios calculated: β1=0.425, β2=0.479, β3=0.091, β4=0.004. The emission cross section at 1068 nm is 6.204×10−20 cm2. 相似文献
8.
Tianxing Lin Jinhai Si Tao Chen Xiaoli Wang Kazuyuki Hirao 《Optics Communications》2007,275(1):230-233
The ultrafast nonlinear optical properties of Bi2O3-B2O3-SiO2 oxide glass were investigated using a femtosecond optical Kerr shutter (OKS) at wavelength of 800 nm. The nonlinear response time of this Bi2O3-doped glass was measured to be <90 fs. The nonlinear refractive-index n2 was estimated to be 1.6 × 10−14 cm2/W. Measurements for the dependence of Kerr signals on the polarization angle between the pump and probe beams showed that the Kerr signals induced by 30-fs pulse laser arose mainly from the photoinduced birefringence effect. 相似文献
9.
We studied the spectroscopic characteristics of telluride glass with the host composition (0.85)TeO2-(0.15)WO3, containing 0.25 and 1.0 mol% thulium oxide (Tm2O3). By analyzing the absorption spectra with the Judd-Ofelt theory, the average radiative lifetimes of 305±7.5 μs and 1.95±0.02 ms were determined for the 3F4 and 3H4 levels, respectively. Measured fluorescence lifetime of the 3F4 level decreased from 218 to 51 μs for the 0.25 and 1.0 mol% Tm2O3 doped samples, respectively, indicating the effect of boosted non-radiative decay at higher doping concentrations. A similar trend was observed for the 3H4 level, where the fluorescence lifetime decreased from 1.86 ms to 350 μs at these concentrations. The quenching of the 1460 nm (3F4→3H4) emission in favor of the 1800 nm (3H4→3H6) emission due to cross relaxation was further evident in the fluorescence spectra of the samples. The calculated stimulated emission cross sections (3.73±0.1×10−21 cm2 at 1460 nm and 6.57±0.07×10−21 cm2 at 1808 nm) reveal the potential importance of the Tm3+:(0.85)TeO2-(0.15)WO3 glass for applications in fiber-optic amplifiers and fiber lasers. 相似文献
10.
In a three-components fluorophosphate glass system, the introduction of H3BO3 brings some valuable influence to the spectroscopic and thermal properties of the glasses. With H3BO3 increases from 2 to 20 mol%, Ω6, Sed4I13/2, FWHM, Tg and fluorescence lifetime change from 3.21×10−20 cm2, 1.77×10−20 cm2, 45 nm, 480 °C and 8.8 ms to 4.66×10−20 cm2, 2.11×10−20 cm2, 50 nm, 541 °C and 7.4 ms, respectively. σabs, σemi, FWHM×τf×σemi has a maximum when H3BO3 is 11 mol%. Tg and Tx−Tg increases with H3BO3 introduction. Results showed that in fluorophosphate glasses, proper amount of B2O3 can be used as a modifier to suppress upconversion and improve spectroscopic properties, broadband property and crystallization stability of the glasses while keeps the fluorescence lifetime relatively high. 相似文献
11.
The comparative investigation on the spectroscopic properties of Er3+ in low phonon energy Bi2O3-GeO2-Ga2O3-Na2O glasses codoped with Ce3+ ion and added with B2O3 component, respectively, is presented. With increasing Ce2O3 content from 0 to 0.8 mol% or B2O3 content from 0 to 15 mol%, the lifetime of Er3+:4I11/2 level decreases dramatically from 607 to 283 μs or to 197 μs, and the upconversion fluorescence is quenched in both glass samples. The nonradiative energy transfer from Er3+:4I11/2→Ce3+:2F5/2 or the enhanced multiphonon relaxation process together with the energy transfer between Er3+ and OH− groups are, respectively, responsible for the results. Meanwhile, the lifetime of 4I13/2 level remains almost unchanged in Er3+/Ce3+-codoped glasses whereas it decreases rapidly in B2O3-added cases. As a result, Er3+/Ce3+ codoping improves the 1.5 μm fluorescence emission intensity, however, B2O3 addition has a negative effect on it. The research results indicate that the Er3+/Ce3+-codoped bismuth glasses will be preferable for obtaining efficient 980 nm pumped EDFA. 相似文献
12.
The ternary MoO3-La2O3-B2O3 glasses containing a large amount of MoO3 (10-50 mol%) are prepared, and their structure and crystallization behavior are examined from the Raman scattering spectrum measurements and X-ray diffraction analyses. It is found that the glass transition and crystallization temperatures and the thermal stability against crystallization decrease with increasing MoO3 content. It is suggested that the main coordination state of Mo6+ ions in the glasses is isolated (MoO4)2− tetrahedral units giving strong Raman bands at 830-860 and 930 cm−1. It is found that the crystalline phases in the crystallized glasses are mainly LaMoBO6 and LaB3O6, and the main crystallization mechanism in MoO3-La2O3-B2O3 glasses is surface crystallization. LaMoBO6 crystals are found to give strong Raman bands at 810-830 and ∼910 cm−1. 相似文献
13.
Keiichi MinamiAkitoshi Hayashi Satoshi UjiieMasahiro Tatsumisago 《Solid State Ionics》2011,192(1):122-125
Electrical and electrochemical properties of the 70Li2S·(30 − x)P2S5·xP2S3 and the 70Li2S·(30 − x)P2S5·xP2O5 (mol%) glass-ceramics prepared by the mechanical milling technique were investigated. Glass-ceramics with 1 mol% P2S3 and 3 mol% P2O5 showed the highest conductivity of 5.4 × 10− 3 S cm− 1 and 4.6 × 10− 3 S cm− 1, respectively. Moreover, these glass-ceramics showed higher electrochemical stability than the 70Li2S·30P2S5 (mol%) glass-ceramic. From the XRD patterns of the obtained glass-ceramics, trivalent phosphorus and oxygen were incorporated into the Li7P3S11 crystal. We therefore presume that the Li7P3S11 analogous crystals, which were formed by incorporating trivalent phosphorus and oxygen into the Li7P3S11 crystal, improve the electrical and electrochemical properties of the glass-ceramics. An all-solid-state cell using the 70Li2S·29P2S5·1P2S3 (mol%) glass-ceramic as solid electrolyte operated under the high current density of 12.7 mA cm− 2 at the high temperature of 100 °C. The cell showed an excellent cyclability of over 700 cycles without capacity loss. 相似文献
14.
The electrical as well as the structural properties of La2O3 thin films on TiN substrates were investigated. Amorphous stoichiometric La2O3 thin films were grown at 300 °C via atomic layer deposition technique by using lanthanum 2,2,6,6-tetramethyl-3,5-heptanedione [La(TMHD)3] and H2O as precursors. Post-annealing of the grown film induced dramatic changes in structural and the electrical properties. Crystalline phases of the La2O3 film emerged with the increase of the post-annealing temperature. Metal-insulator-metal (MIM) capacitor was fabricated to measure the electrical properties of the grown film. The dielectric constant of the La2O3 thin films increased with annealing temperature to reach the value of 17.3 at 500 °C. The leakage current density of the film post-annealed at 400 °C was estimated to be 2.78 × 10−10 and 2.1 × 10−8 A/cm2 at ±1 V, respectively. 相似文献
15.
In this study, the principal role of Al2O3 on the features of the photoluminescence spectra of Tm3+ ion and upconversion phenomenon in Tm3+ and Er3+ codoped CaF2−Al2O3−P2O5−SiO2 glass system has been investigated. The concentration of Al2O3 is varied from 2 to 10 mol% while that of Er3+ and Tm3+ is fixed. IR and Raman spectral studies have indicated that there is a gradual increase in the degree of disorder in the glass network with increase in the concentration of Al2O3 up to 6.0 mol%. This is attributed to the presence of Al3+ ions in octahedral positions in larger proportions. When the glasses are doped with Tm3+ ions, the blue and red emissions were observed, whereas in Er3+ doped glasses blue, green and red emissions were observed. When the glasses are codoped with Tm3+ and Er3+ ions and excited at 790 nm, all the three emission lines were observed to be reinforced, especially in the glasses mixed with 6.0 mol% of Al2O3. The IR emission band detected at about 1.8 μm due to 3F4→3H6 transition of Tm3+ ions is also observed to be strengthened due to codoping. The reasons for enhancement in the intensity of various emission bands due to codoping have been identified and discussed with the help of rate equations for various emission transitions. 相似文献
16.
Xiao WangZuimin Jiang Fei Xu Zhongquan MaRun Xu Bin YuMingzhu Li Lingling ZhengYongliang Fan Jian HuangFang Lu 《Applied Surface Science》2012,258(6):1896-1901
Alternately Er doped Si-rich Al2O3 (Er:SRA) multilayer film, consisting of alternate Er-Si-codoped Al2O3 (Er:Si:Al2O3) and Si-doped Al2O3 (Si:Al2O3) sublayers, has been synthesized by co-sputtering from separated Er, Si, and Al2O3 targets. The dependence of Er3+ related photoluminescence (PL) properties on annealing temperatures over 700-1100 °C was studied. The maximum intensity of Er3+ PL, about 10 times higher than that of the monolayer film, was obtained from the multilayer film annealed at 950 °C. The enhancement of Er3+ PL intensity is attributed to the energy transfer from the silicon nanocrystals in the Si:Al2O3 sublayers to the neighboring Er3+ ions in the Er:Si:Al2O3 sublayers. The PL intensity exhibits a nonmonotonic temperature dependence: with increasing temperature, the integrated intensity almost remains constant from 14 to 50 K, then reaches maximum at 225 K, and slightly increases again at higher temperatures. Meanwhile, the PL integrated intensity at room temperature is about 30% higher than that at 14 K. 相似文献
17.
Y2O3 transparent ceramics with different Nd concentration (0.1-7.0at%) were fabricated using ZrO2 as additive. All the samples exhibit high transparency over a broad spectral region. The elements (Y, O and Nd) are uniformly distributed in the ceramic body, and the average grain size increases with Nd content. Based on the absorption spectrum, the Judd-Ofelt intensity parameters are calculated (Ω2=4.364×10−20 cm2, Ω4=3.609×10−20 cm2 and Ω6=2.919×10−20 cm2). The absorption coefficients increase linearly with Nd3+ doping concentration. The absorption cross-section at 804 nm and stimulated emission cross-section at 1078 nm are calculated to be 1.54×10−20 and 7.24×10−20 cm2, respectively. All the emission bands exhibit the highest emission intensities with 1.0at% Nd3+ ion content, while the lifetime decreases dramatically from 321.5 μs (0.1at% Nd) to 17.9 μs (7.0at% Nd). According to the emission spectra and measured lifetime, the optimum doping concentration of Nd3+ ion in Y2O3 transparent ceramic might be around 1.0at%. 相似文献
18.
CdIn2O4 thin films were prepared by direct-current (DC) reactive magnetron sputtering. The structure, surface morphology and the chemical composition of the thin films were analyzed by X-ray diffraction (XRD), atomic force microscope (AFM) and X-ray photoelectron spectroscopy (XPS), respectively. The electrical properties of the films prepared in different oxygen concentration and annealing treatment were determined, and the effects of the preparing conditions on the structure and electrical properties were also explored. It indicates that the CdIn2O4 thin films with uniform and dense surface morphology contain mainly CdIn2O4, In2O3 phases, and CdO phase is also observed. The XPS analysis confirms the films are in oxygen-deficient state. The electrical properties of these films significantly depend on the preparing conditions, the resistivity of the films with the oxygen concentration of 4.29% is 2.95 × 10−4 Ω cm and the Hall mobility is as high as 60.32 cm2/V s. Annealing treatment can improve the electrical performance of the films. 相似文献
19.
Glass formation has been investigated in the Sb2O3-ZnBr2 binary system. Vitreous samples have been obtained for batches containing 20-90 mol% Sb2O3. Chemical analysis shows that bromine concentration is smaller than expected and real compositions belong to the Sb2O3-ZnBr2-ZnO ternary system. However, the discrepancy between nominal and analyzed compositions is fair for Sb2O3 content larger than 50 mol%. Optical transmission lies between 400 nm and 7 μm and refractive index ranges from 2.0 to 2.1. Glass transition occurs around 300 °C, and crystallization exotherm does not appear in the differential scanning calorimetry scan at 10 K s−1 for samples containing 50-60 mol% Sb2O3. Thermal expansion varies between 120 and 220×10−7 K−1 as antimony content decreases. Microhardness is close to 200 kg/mm2. These glasses have low phonon energy and make potential materials for infrared transmission and active fibers. 相似文献
20.
Physical and electrical properties of sputtered deposited Y2O3 films on NH4OH treated n-GaAs substrate are investigated. The as-deposited films and interfacial layer formation have been analyzed by using X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS). It is found that directly deposited Y2O3 on n-GaAs exhibits excellent electrical properties with low frequency dispersion (<5%), hysteresis voltage (0.24 V), and interface trap density (3 × 1012 eV−1 cm−2). The results show that the deposition of Y2O3 on n-GaAs can be an effective way to improve the interface quality by the suppression on native oxides formation, especially arsenic oxide which causes Fermi level pinning at high-k/GaAs interface. The Al/Y2O3/n-GaAs stack with an equivalent oxide thickness (EOT) of 2.1 nm shows a leakage current density of 3.6 × 10−6 A cm−2 at a VFB of 1 V. While the low-field leakage current conduction mechanism has been found to be dominated by the Schottky emission, Poole-Frenkel emission takes over at high electric fields. The energy band alignment of Y2O3 films on n-GaAs substrate is extracted from detailed XPS measurements. The valence and conduction band offsets at Y2O3/n-GaAs interfaces are found to be 2.14 and 2.21 eV, respectively. 相似文献