溅射制备Ta2O5薄膜的表面形貌与光学特性

在室温条件下利用溅射Ta₂O₅靶材的方法制备了Ta₂O₅薄膜,并采用将薄膜两侧的反射率光谱进行比较的简便方法分析评估薄膜的光吸收,发现溅射制备薄膜的额外光吸收源是溅射引起的缺氧形成的,选择适当的溅射功率和含氧比例的工作气体能有效地消除这些缺陷、不用任何加温处理就可制备得到表面平坦和高致密度的高品质Ta₂O₅薄膜. 关键词： 2O₅薄膜')" href="#">Ta₂O₅薄膜 光吸收 表面形貌 磁控溅射     

基于TaCl5的Ta2O2气凝胶制备工艺

主要介绍了以TaCl5为前驱体,低分子醇类为溶剂,分别采用环氧丙烷和环氧氯丙烷作为凝胶促进剂制备Ta2O2湿凝胶,湿凝胶经过CO2超临界干燥而获得白色Ta2O2气凝胶。透射电镜图谱表明气凝胶是由粒度为10～20 nm的颗粒堆积而成。N2等温吸附-脱附分析表明,气凝胶的比表面积为800～900 m2/g。     

不同酸催化条件下Ta2O5气凝胶的制备

采用溶胶-凝胶技术,以乙醇钽为前躯体,乙醇为溶剂,分别以盐酸、硝酸、硫酸为催化剂,结合CO2超临界干燥技术制备了Ta2O5气凝胶。研究发现：硫酸作催化剂的体系,其胶凝时间远远小于其他体系,且溶剂交换及超临界干燥过程中的收缩开裂现象明显改善;扫描电镜分析结果显示,硫酸为催化剂制备的Ta2O5气凝胶骨架颗粒间存在较严重的团簇现象,比表面积约167 m2/g,明显低于以盐酸、硝酸为催化剂的体系。X射线光电子能谱测试结果显示,Ta2O5气凝胶中无相应的Cl元素或N元素残留,而S元素则基本上滞留在Ta2O5气凝胶中。说明S元素进入了Ta-O-Ta交联结构,正是因为这种结构的引入,Ta2O5气凝胶的收缩龟裂现象得以明显改善并呈现出相对较高的力学性能。     

不同酸催化条件下Ta2O5气凝胶的制备

采用溶胶-凝胶技术,以乙醇钽为前躯体,乙醇为溶剂,分别以盐酸、硝酸、硫酸为催化剂,结合CO2超临界干燥技术制备了Ta2O5气凝胶。研究发现:硫酸作催化剂的体系,其胶凝时间远远小于其他体系,且溶剂交换及超临界干燥过程中的收缩开裂现象明显改善;扫描电镜分析结果显示,硫酸为催化剂制备的Ta2O5气凝胶骨架颗粒间存在较严重的团簇现象,比表面积约167 m2/g,明显低于以盐酸、硝酸为催化剂的体系。X射线光电子能谱测试结果显示,Ta2O5气凝胶中无相应的Cl元素或N元素残留,而S元素则基本上滞留在Ta2O5气凝胶中。说明S元素进入了Ta-O-Ta交联结构,正是因为这种结构的引入,Ta2O5气凝胶的收缩龟裂现象得以明显改善并呈现出相对较高的力学性能。     

金属醇盐法制备Ta2O5气凝胶

以乙醇钽为前驱物,采用金属醇盐溶胶-凝胶技术,获得了Ta2O5湿凝胶,分析了不同条件下的溶胶-凝胶过程,并初步探讨了凝胶过程机理。Ta2O5的溶胶-凝胶过程主要受到水量、催化剂用量及钽源浓度等因素的影响：体系在强酸性条件下凝胶,且随着酸性的增强,体系凝胶时间明显缩短;当水量较少时,凝胶时间随水量的增加而增加,但当水量增加到一定程度时,体系凝胶时间基本不变;实验证明,通过增大溶剂用量,体系凝胶时间延长,气凝胶理论密度降低。通过对溶胶-凝胶过程的控制,结合超临界干燥技术,获得了密度低至44 mg/cm3的Ta2O5气凝胶样品。     

Ta2O5-PMMA复合栅绝缘层对OFETs性能的影响

选用五氧化二钽（Ta₂O₅）-聚甲基丙烯酸甲酯（PMMA）复合材料作为栅绝缘层制备了并五苯有机场效应晶体管（OFETs）。通过在Ta₂O₅表面旋涂一层PMMA可以降低栅绝缘层的表面粗糙度,增大其场效应晶体管的迁移率。研究了厚度在20~60 nm范围内的PMMA对复合绝缘层表面形貌、粗糙度以及器件电学性能的影响。结果表明,当PMMA厚度为40 nm时,器件的电学性能最佳。与单一的Ta₂O₅栅绝缘层器件相比,其场效迁移率由4.2×10^-2 cm²/（V·s）提高到0.31 cm²/（V·s）;栅电压增加到-20 V时,开关电流比由2.9×10²增大到2.9×10⁵。     

基于旋涂法和电子束蒸发法制备的V2O5/Ag/V2O5叠层透明导电薄膜

利用溶胶-凝胶技术与电子束蒸镀相结合的方法在常温下制备了叠层V₂O₅/Ag/V₂O₅（VAV）透明导电薄膜,研究了各层薄膜厚度对叠层结构光电特性的影响。用原子力显微镜、紫外-可见光分光光度计、四探针电阻仪及开尔文探针对样品的表面形貌、光电性能及功函数等性质进行了表征。实验结果表明,该薄膜具有良好的光学和电学性质,可见光（380~780 nm）平均透过率达75%,迁移率为16.89 cm²/（V·s）,载流子浓度为－1.043×10²² cm^-3,方块电阻值为15.1 Ω/□,功函数为5.17 eV。该制备方法降低了V₂O₅薄膜的工艺制备难度,为该材料在太阳能电池中的应用创造了良好的前期基础。     

新的压电薄膜——Ta2O5

据报道,日本Yasuhiko Nakagawa和Yasuo Gomi用磁控反应直流二极管溅射法将Ta_2O_5,沉积在石英基片上,得到了单晶薄膜,并且首次观察到了这种薄膜的压电现象.用叉指换能器在Ta_2O_5薄膜上成功地激发了声表面波.在Ta_2O_5/熔石英基片上,当薄膜厚度h在hk(=2πh/λ)=1.0时,其机电耦合系数k~2=0.5％,它可与熔石英基片上ZnO薄膜的机电耦合系数相比拟. 利用Ta_2O_5单晶的X射线衍射数据,推断出Ta_2O_5     

SrBi2Ta2O9/Bi4Ti3O12复合铁电薄膜的制备与特性研究

采用溶胶凝胶工艺在p-Si衬底上制备了SrBi₂Ta₂O₉/Bi₄Ti₃O₁₂复合铁电薄膜. 研究了SrBi₂Ta₂O₉/Bi₄Ti₃O₁₂复合薄膜的微观结构与生长行为、铁电性能和疲劳特性. 研究表明: Si衬底Bi₄Ti< 关键词： 2Ta₂O₉')" href="#">SrBi₂Ta₂O₉ 4Ti₃O₁₂')" href="#">Bi₄Ti₃O₁₂ 复合铁电薄膜 溶胶凝胶工艺     

用于α-Al2O3分子动力学模拟的长程Finnis-Sinclair势函数

用金属势函数描述氧化物是实现金属-氧化物界面分子动力学模拟的关键.基于此,通过拟合α-Al₂O₃的晶格能、晶格常数、弹性常数,获得了一套用于描述α-Al₂O₃的长程Finnis-Sinclair（F-S）势.通过与已报道的描述α-Al₂O₃的EAM势、Glue势和modified Matsui（m-Matsui）势的比较,结果达到或优于前人的结果.进而,在300 K的温度下对 关键词： 长程F-S势 2O₃')" href="#">α-Al₂O₃ 2O₃界面')" href="#">Fe-Al₂O₃界面 2O₃界面')" href="#">Al-Al₂O₃界面     

Structural and compositional changes in ion-bombarded Ta2O5

A detailed study of the effect of heavy-ion bombardment on Ta₂O₅ has been undertaken using a combination of radioactive tracer techniques, electron microscopy, and Rutherford backscattering. Crystalline Ta₂O₅ is amorphized at ~6 × 10¹³ ions cm^?2, while at a dose of ~5 × 10¹⁶ ions cm^?2 the electron microscopy reveals the development of random grains of a new crystalline phase. By ~1 × 10¹⁷ ions cm^?2 the grains are not yet overlapping but still yield a diffraction pattern consistent with either δ-Ta-O (not to be confused with TaO) or Ta_1?xO₂, thus indicating that Ta₂O₅, like most other transition-metal oxides, is subject to preferential sputtering. Preferential sputtering was confirmed by backscattering analysis of specimens bombarded to high doses, where the average surface composition was found to be Ta_1.8±0.2O₂ or, equivalently, Ta₂O_2.2±0.2. The surface alteration had an average composition independent of the mass and energy of the incident ions.     

Comparison of laser-induced damage in Ta2O5 and Nb2O5 single-layer films and high reflectors

Ta2O5 and Nb2O5 films are deposited on BK7 glass substrates using an electron beam evaporation method and are annealed at 673 K in the air.In this letter,comparative studies of the optical transmittance,microstructure,chemical composition,optical absorption,and laser-induced damage threshold(LIDT) of the two films are conducted.Findings indicate that the substoichiometric defect is very harmful to the laser damage resistance of Ta2O5 and Nb2O5 films.The decrease of absorption improves the LIDT in films deposited by the same material.However,although the absorption of the Ta2O5 single layer is less than that of the Nb2O5 single layer,the LIDT of the former is lower than that of the latter.High-reflective(HR) coatings have a higher LIDT than single layers due to the thermal dissipation of the SiO2 layers and the decreased electric field intensity(EFI).In addition,the Nb2O5 HR coating achieves the highest LIDT at 25.6 J/cm 2 in both single layers and HR coatings.     

Waveguiding and photoluminescence in Er-doped Ta2O5 planar waveguides

The optimization of erbium-doped Ta₂O₅ thin film waveguides deposited by magnetron sputtering onto thermally oxidized silicon wafer is described. Optical constants of the film were determined by ellipsometry. For the slab waveguides, background losses below 0.4 dB/cm at 633 nm have been obtained before post-annealing. The samples, when pumped at 980 nm yielded a broad photoluminescence spectrum (FWHM∼50 nm) centred at 1534 nm, corresponding to ⁴I_13/2-⁴I_15/2 transition of Er³⁺ ion. The samples were annealed up to 600 °C and both photoluminescence power and fluorescence lifetime increase with post-annealing temperature and a fluorescence lifetime of 2.4 ms was achieved, yielding promising results for compact waveguide amplifiers.     

Emission features of Ho ion in Nb2O5, Ta2O5 and La2O3 mixed Li2O-ZrO2-SiO2 glasses

Li₂O-ZrO₂-SiO₂: Ho³⁺ glasses mixed with three interesting d-block elemental oxides, viz., Nb₂O₅, Ta₂O₅ and La₂O₃, were prepared. Optical absorption and photoluminescence spectra of these glasses have been recorded at room temperature. The luminescence spectra of Nb₂O₅ and Ta₂O₅ mixed Li₂O-ZrO₂-SiO₂ glasses (free of Ho³⁺ ions) have also exhibited broad emission band in the blue region. This band is attributed to radiative recombination of self-trapped excitons (STEs) localized on substitutionally positioned octahedral Ta⁵⁺ and Nb⁵⁺ ions in the glass network. The Judd-Ofelt theory was successfully applied to characterize Ho³⁺ spectra of all the three glasses. From this theory various radiative properties, like transition probability A, branching ratio β_r and the radiative lifetime τ_r, for ⁵S₂ emission levels in the spectra of these glasses have been evaluated. The radiative lifetime for ⁵S₂ level of Ho³⁺ ions has also been measured and quantum efficiencies were estimated. Among the three glasses studied the La₂O₃ mixed glass exhibited the highest quantum efficiency. The reasons for such higher value have been discussed based on the relationship between the structural modifications taking place around the Ho³⁺ ions.     

Ta2O5/MgF2异质结构三维光子晶体的偏振性

为了在可见及近红外波段得到具有良好带隙结构的三维光子晶体,利用传输矩阵法分析了MgF₂、Ta₂O₅ 以及Ta₂O₅/MgF₂异质结构三维光子晶体的带隙性质.结果表明：Ta₂O₅/MgF₂异质结构三维光子晶体在820~1 020 nm的近红外波段TM模式下具有不受入射光方向影响的全方位光子带隙.该结构有望用于制作近红外光波段的偏振器件.     

渐变折射率Ta2O5/SiO2薄膜多脉冲激光损伤特性

采用离子束溅射（IBS）的方式,制备了1064 nm高反射Ta2O5/SiO2渐变折射率光学薄膜。对其光学性能和在基频多脉冲下抗损伤性能进行了分析。 通过渐变折射率的设计方式,很好地抑制了边带波纹,增加了1064 nm反射率。通过对损伤阈值的分析发现,随着脉冲个数的增加,损伤阈值下降明显;但是在20个脉冲数后,损伤阈值（维持在22 J/cm2左右）几乎保持不变直到100个脉冲数。通过Leica显微镜对损伤形貌的观察,发现损伤诱因是薄膜表面的节瘤缺陷。通过扫描电镜（SEM）以及聚集离子束（FIB）对薄膜表面以及断面的观察,证实了薄膜的损伤起源于薄膜表面的节瘤缺陷。进一步研究得出,渐变折射率薄膜在基频光单脉冲下损伤主要是由初始节瘤缺陷引起的,在后续多脉冲激光辐照下初始节瘤缺陷引起烧蚀坑的面积扩大扫过薄膜上的其他节瘤缺陷,引起了其他节瘤缺陷的喷射使损伤加剧,造成损伤的累积效应。     

渐变折射率Ta_2O_5/SiO_2薄膜多脉冲激光损伤特性

采用离子束溅射(IBS)的方式,制备了1064nm高反射Ta2O5/SiO2渐变折射率光学薄膜。对其光学性能和在基频多脉冲下抗损伤性能进行了分析。通过渐变折射率的设计方式,很好地抑制了边带波纹,增加了1064nm反射率。通过对损伤阈值的分析发现,随着脉冲个数的增加,损伤阈值下降明显;但是在20个脉冲数后,损伤阈值(维持在22J/cm2左右)几乎保持不变直到100个脉冲数。通过Leica显微镜对损伤形貌的观察,发现损伤诱因是薄膜表面的节瘤缺陷。通过扫描电镜(SEM)以及聚集离子束(FIB)对薄膜表面以及断面的观察,证实了薄膜的损伤起源于薄膜表面的节瘤缺陷。进一步研究得出,渐变折射率薄膜在基频光单脉冲下损伤主要是由初始节瘤缺陷引起的,在后续多脉冲激光辐照下初始节瘤缺陷引起烧蚀坑的面积扩大扫过薄膜上的其他节瘤缺陷,引起了其他节瘤缺陷的喷射使损伤加剧,造成损伤的"累积效应"。     

Structure and optical analysis of Ta2O5 deposited on infrasil substrate

Electron beam gun technique was used to prepare Ta₂O₅ thin films onto infrasil substrates of thicknesses 333 and 666 nm. The structure characterization was investigated using X-ray diffraction patterns. Transmittance measurements in the wavelength range (240-2000 nm) were used to calculate the refractive index n and the absorption index k depending on Swanepole's method. The dispersion curve of the refractive index shows an anomalous dispersion in the absorption region and a normal one in the transparent region. The analysis of the optical absorption data revealed that the optical band gap E_g was indirect transition. It was found that the refractive index dispersion data obeyed the single oscillator of the Wemple-DiDomenico model, from which the dispersion parameters (E_o and E_d) and the high frequency dielectric constant were determined. The electric free carrier susceptibility and the carrier concentration to the effective mass ratio were estimated according to the model of Spitzer and Fan. Graphical representation of the relaxation time as a function of photon energy was also presented.