花状掺杂W-VO$lt;sub$gt;2$lt;/sub$gt;/ZnO热致变色纳米复合薄膜研究

为解决掺杂引起的二氧化钒薄膜的红外调制幅度下降以及二氧化钒复合薄膜相变温度需要进一步降低等问题, 采用纳米结构、掺杂改性和复合结构等多种机理协同作用的方案, 利用共溅射氧化法, 先在石英玻璃上制备高(002)取向的ZnO薄膜, 再在ZnO层上室温共溅射沉积钒钨金属薄膜, 最后经热氧化处理获得双层钨掺杂W-VO₂/ZnO纳米复合薄膜. 利用X射线衍射、X射线光电子能谱、扫描电镜和变温光谱分析等对薄膜的结构、组分、形貌和光学特性进行了分析. 结果显示, W-VO₂/ZnO 纳米复合薄膜呈花状结构, 取向性提高, 在保持掺杂薄膜相变温度(约39 ℃)和热滞回线宽度(约6 ℃)较低的情况下, 其相变前后的红外透过率差量增加近2倍, 热致变色性能得到协同增强. 关键词： 2')" href="#">VO₂ ZnO W掺杂 热致变色     

VO$lt;sub$gt;2$lt;/sub$gt;/AZO复合薄膜的制备及其光电特性研究

采用直流磁控溅射和后退火氧化的方法在掺铝氧化锌(AZO)导电玻璃上制备了二氧化钒(VO₂)薄膜,研究了不同的退火温度、退火时间对VO₂/AZO复合薄膜制备的影响,并对复合薄膜的结构、组分、光电特性进行了测试与分析. 结果表明,导电玻璃上的AZO没有改变VO₂的取向生长,但明显改变了VO₂薄膜的表面形貌特征. 与用相同工艺和条件在普通玻璃基底上制备的VO₂薄膜相比,VO₂/AZO复合薄膜的相变温度降低约25 ℃,热滞回线宽度收窄至6 ℃,相变前后可见光透过率均在50%以上,1500 nm处红外透过率约为55%和21%,电阻率变化达3 个数量级. 该复合薄膜表面平滑致密,制备工艺简单,性能稳定,可应用于新型光电器件. 关键词： 2')" href="#">VO₂ AZO 热致相变 光电特性     

用于红外激光防护的高开关率VO2薄膜

采用反应离子束溅射和后退火处理技术在石英玻璃基底上制备了具有纳米粒子的二氧化钒(VO₂)薄膜. 该薄膜具有半导体-金属相变特性,在3 μm处的开关率达到76.6%。 热致相变实验结果给出了准确的最佳退火温度为465 ℃. 仿真、热致相变和光致相变实验都显示VO₂薄膜在红外波段具有很高的光学开关特性. 光电池防护实验结果显示VO₂薄膜将硅光电池的抗干扰能力提升了2.6倍, 证明了VO₂在激光防护中的适用性. 采用连续可调节系统研究得到VO₂在室温条件下的相变阈值功率密度为4.35 W/cm², 损伤阈值功率密度为404 W/cm²。 低相变阈值和高损伤阈值都进一步证明VO₂薄膜适用于激光防护系统。本实验制备的VO₂薄膜在光开关、光电存储器、智能窗等方面也具有广泛的应用价值.     

VO2热致变色薄膜的结构和光电特性研究

用磁控溅射方法制备了VO₂热致变色薄膜.用X射线衍射、X射线光电子谱和原子力显微镜对薄膜的宏观及微观结构进行了分析，表明VO₂薄膜纯度高、相结构单一、结晶度好.薄膜的光透过率在2000nm处相变前后改变了42%，高/低温电阻率变化达到三个数量级以上.薄膜的光透过谱和相变过程中电学性质变化的研究与结构分析结果相一致. 关键词：     

磁控溅射制备W掺杂VO2/FTO复合薄膜及其性能分析

为了获得相变温度低且热致变色性能优越的光学材料, 室温下在F:SnO₂ (FTO)导电玻璃基板表面沉积钨钒金属膜, 再经空气气氛下的热氧化处理, 制备了W掺杂VO₂/FTO复合薄膜, 利用X射线光电子能谱、X射线衍射和扫描电镜对薄膜的结构和表面形貌进行了分析. 结果表明: 高温热氧化处理过程中没有生成W, F, V混合氧化物, W以替换V原子的方式掺杂. 与采用相同工艺和条件制备的纯VO₂/FTO复合薄膜相比, W掺杂VO₂薄膜没有改变晶面取向, 仍具有(110)晶面择优取向, 相变温度下降到35 ℃左右, 热滞回线收窄到4 ℃, 高低温下的近红外光透过率变化量提高到28%. 薄膜的结晶程度明显提高, 表面变得平滑致密, 具有很好的一致性, 对光电薄膜器件的设计开发和工业化生产具有重要意义. 关键词： W掺杂 2')" href="#">VO₂ FTO导电玻璃 磁控溅射     

金属Pt薄膜上二氧化钒的制备及其电致相变性能研究

通过引入SiO₂氧化物缓冲层, 在金属Pt电极上利用射频磁控溅射技术成功制备出高质量的VO₂薄膜. 详细研究了SiO₂厚度对VO₂薄膜的晶体结构、微观形貌和绝缘体–金属相变(MIT)性能的影响. 结果表明厚度0.2 μm以上的SiO₂缓冲层能够有效 消除VO₂薄膜与金属薄膜之间的巨大应力, 制备出具有明显相变特性的VO₂薄膜. 当缓冲层达到0.7 μm以上, 获得的薄膜具有明显的(011)晶面择优取向, 表面平整致密, 相变前后电阻率变化达到3个数量级以上. 基于该技术制备了Pt-SiO₂/VO₂-Au三明治结构, 通过在垂直膜面方向施加很小的驱动电压, 观察到明显的阶梯电流跳跃, 证实实现了电致绝缘体–金属相变过程. 该薄膜制备工艺简单, 性能稳定, 器件结构灵活可应用于集成式电控功能器件. 关键词： 二氧化钒薄膜 相变特性 电致相变 阈值电压     

硅基二氧化钒相变薄膜电学特性研究

本文以原子层沉积超薄氧化铝(Al₂ O₃)为过渡层, 采用射频反应磁控溅射法在硅半导体基片上制备了颗粒致密并具有(011)择优取向的二氧化钒(VO₂)薄膜. 该薄膜具有显著的绝缘体–金属相变特性, 相变电阻变化超过3 个数量级, 热滞回线宽度约为6℃. 基于VO₂薄膜构建了平面二端器件并测试了不同温度下I-V曲线, 观测到超过2个数量级的电流跃迁幅度, 显示了优越的电致相变特性. 室温下电致相变阈值电压为8.6 V, 电致相变弛豫电压宽度约0.1 V. 随着温度升高到60℃, 其电致相变所需要的阈值电压减小到2.7 V. 本实验制备的VO₂薄膜在光电存储、开关、太赫兹调控器件中具有广泛的应用价值.     

热致变色纳米节能薄膜红外光学特性

采用室温溅射沉积和空气热氧化方法低成本地制备出纳米结构热致变色节能薄膜。利用扫描电子显微镜、X射线衍射仪、激光拉曼光谱仪和红外光谱分析仪等对其特性进行测试分析,研究了热氧化退火与VO2薄膜的微结构和热致红外开关特性的内在关系,找出了直接影响薄膜的晶粒尺寸、晶格结构、组分、热滞回线和红外透射比等的主要因素及其控制方法,获得了最佳工艺参数并在玻璃上制备出高能效的纳米VO2热致变色节能薄膜。根据X射线衍射谱和拉曼光谱结果,利用相关公式计算得到VO2的平均晶粒大小约为45 nm。薄膜在2.5μm波长处相变前后红外透射比差量超过50%,相变温度为39℃,可见光透射比约达53%,显示了很好的热致变色性能。     

VO2金属-绝缘体相变机理的研究进展

VO₂是一种热致相变金属氧化物. 在341 K附近, VO₂发生由低温绝缘体相到高温金属相的可逆转变, 同时伴随着光学、电学和磁学等性质的可逆突变, 这种独特的性质使得VO₂在光电开关材料、智能玻璃、存储介质材料等领域有着广阔的应用前景. 因此, VO₂金属-绝缘体可逆相变一直是人们的研究热点, 但其相变机理至今未有定论. 首先, 简要概述了VO₂相变时晶体结构和能带结构的变化情况: 从晶体结构来讲, 相变前后VO₂从低温时的单斜相VO₂(M)转变为高温稳定的金红石相VO₂(R), 在一定条件下此过程也可能伴随着亚稳态单斜相VO₂(B)与四方相VO₂(A)的产生; 从能带结构来看, VO₂处于低温单斜相时, 其d_//能带和π^*能带之间存在一个禁带, 带宽约为0.7 eV, 费米能级恰好落在禁带之间, 表现出绝缘性, 而在高温金红石相时, 其费米能级落在π^*能带与d_//能带之间的重叠部分, 因此表现出金属导电性. 其次, 着重总结了VO₂相变物理机理的研究现状. 主要包括: 电子关联驱动相变、结构驱动相变以及电子关联和结构共同驱动相变的3种理论体系以及支撑这些理论体系的实验结果. 文献报道争论的焦点在于, VO₂是否是Mott绝缘体以及结构相变与MIT相变是否精确同时发生. 最后, 展望了VO₂材料研究的发展方向.     

基于FTO/VO2/FTO结构的VO2薄膜电压诱导相变光调制特性

采用直流磁控溅射和后退火工艺在掺氟的SnO₂(FTO)导电玻璃衬底上制备VO₂薄膜, 研究了不同退火时间和不同比例的氮氧气氛对VO₂薄膜性能的影响, 对VO₂薄膜的结晶取向、表面形貌、表面元素的相对含量和透过率随波长变化进行了测试分析, 结果表明在最佳工艺条件下制备得到了组分相对单一的VO₂薄膜. 基于FTO/VO₂/FTO结构在VO₂薄膜两侧的透明导电膜上施加电压并达到阈值电压时, 观察到了明显的电流突变. 当接触面积为3 mm×3 mm时, 阈值电压为1.7 V, 阈值电压随接触面积的增大而增大. 与不加电压的情况相比, FTO/VO₂/FTO结构在电压作用下高低温的红外透过率差值可达28%, 经反复施加电压, 该结构仍保持性能稳定, 具有较强的电致调控能力.     

Growth of b-axis oriented VO2 thin films on glass substrates using ZnO buffer layer

VO₂ thin films are grown on glass substrates by pulsed laser deposition using vanadium metal as a target. In this study, a ZnO thin film was used as a buffer layer for the growth of VO₂ thin films on glass substrates. X-ray diffraction studies showed that the VO₂ thin film had b-axis preferential orientation on a c-axis oriented ZnO buffer layer. The thickness of the ZnO buffer layer and the oxygen pressure during VO₂ deposition were optimized to grow highly b-axis oriented VO₂ thin films. The metal-insulator transition properties of the VO₂ film samples were investigated in terms of infrared reflectance and electrical resistance with varying temperatures.     

Propagations of Rayleigh and Love waves in ZnO films/glass substrates analyzed by three-dimensional finite element method

Propagation characteristics of surface acoustic waves(SAWs) in ZnO films/glass substrates are theoretically investigated by the three-dimensional(3D) finite element method. At first, for(11ˉ20) ZnO films/glass substrates, the simulation results confirm that the Rayleigh waves along the [0001] direction and Love waves along the [1ˉ100] direction are successfully excited in the multilayered structures. Next, the crystal orientations of the ZnO films are rotated, and the influences of ZnO films with different crystal orientations on SAW characterizations, including the phase velocity, electromechanical coupling coefficient, and temperature coefficient of frequency, are investigated. The results show that at appropriate h/λ, Rayleigh wave has a maximum k~2 of 2.4% in(90°, 56.5°, 0°) ZnO film/glass substrate structure; Love wave has a maximum k~2 of 3.81% in(56°, 90°, 0°) ZnO film/glass substrate structure. Meantime, for Rayleigh wave and Love wave devices, zero temperature coefficient of frequency(TCF) can be achieved at appropriate ratio of film thickness to SAW wavelength. These results show that SAW devices with higher k~2 or lower TCF can be fabricated by flexibly selecting the crystal orientations of ZnO films on glass substrates.     

Influence of Concentration of Vanadium in Zinc Oxide on Structural and Optical Properties with Lower Concentration

ZnO films doped with different vanadium concentrations are deposited onto glass substrates by dc reactive magnetron sputtering using a zinc target doped with vanadium. The vanadium concentrations are examined by energy dispersive spectroscopy （EDS） and the charge state of vanadium in ZnO thin films is characterized by x-ray photoelectron spectroscopy. The results of x-ray diffraction （XRD） show that all the films have a wurtzite structure and grow mainly in the c-axis orientation. The grain size and residual stress in the deposited films are estimated by fitting the XRD results. The optical properties of the films are studied by measuring the transmittance. The optical constants （refractive index and extinction coefficient） and the film thickness are obtained by fitting the transmittance. All the results are discussed in relation with the doping of the vanadium.     

纳米ZnO和ZnO-SiO2复合薄膜的光学性质研究

通过溶胶凝胶(sol-gel)法分别在玻璃衬底上制备了ZnO纳米薄膜和ZnO-SiO₂纳米复合薄膜,并利用紫外-可见光分光光度计对薄膜的光学性能进行了分析.可见光-紫外透射谱显示,随着ZnO溶胶浓度从0.7mol/L降低到0.006mol/L,制备的ZnO薄膜从只出现一个380nm(对应的光学禁带宽度为3.27eV)左右的吸收边到在380和320nm(对应的光学禁带宽度为3.76eV)左右各出现一个吸收边,并且随着ZnO溶胶浓度的降低,在380—320nm波段内的透过率明显提高.而Z 关键词： 纳米ZnO 2复合薄膜')" href="#">ZnO-SiO₂复合薄膜 溶胶凝胶法 透射率     

Characterization of ZnO thin films grown on various substrates by RF magnetron sputtering

In this study we investigated properties of ZnO thin films deposited on both oxygen-containing substrates and a substrate without oxygen content at various O₂/Ar reactant gas ratios. Deposition of ZnO on indium-tin oxide (ITO) resulted in the best crystallinity, whereas the least degree of crystallization was observed from ZnO deposited on glass. All the films were found to have compressive stress, which was relieved by annealing in O₂ environment. ZnO films deposited on glass revealed p-type conductivity when prepared at O₂/Ar ratio of 0.25 whereas those on SiN_x yielded p-type conductivity when prepared at O₂/Ar ratio of 4. In addition, shallower oxygen interstitial seemed to be found from films with better crystallinity. The largest shift in binding energy of Zn_2p3/2 was observed from ZnO prepared on glass at O₂/Ar ratio of 0.25, whereas that of O_1s was obtained from ZnO deposited on SiN_x at O₂/Ar ratio of 4. A model was proposed in terms of O₂ diffusion and hydrogen desorption in order to account for the observed property variations depending on substrates and O₂/Ar ratios.     

The structure and optical characters of the ZnO film grown on GaAs/Al2O3 substrate

In this paper ZnO films are grown on GaAs/Al₂O₃ substrates at different temperature by metal-organic chemical vapor deposition (MOCVD). The GaAs/Al₂O₃ substrates are formed by depositing GaAs layer (∼35 nm) on the Al₂O₃ substrate. The results of X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) demonstrate that most of the Ga and As atoms form Ga-As bond and the GaAs layer does not present any orientation. The characters of the ZnO films grown on GaAs/Al₂O₃ substrates are investigated by XRD, photoluminescence (PL), atomic force microscopy (AFM) and Raman scattering. Compared with ZnO film grown on Al₂O₃ substrate, ZnO film prepared by our fabrication scheme has good crystal and optical quality. Meanwhile its grain size becomes bigger according to the AFM image. Raman analysis indicates that the intrinsic defects and the in-plane tensile stress are obviously reduced in ZnO/GaAs/Al₂O₃ samples.     

溶胶-凝胶制备ZnO-SiO2复合膜的量子效应和上转换发光

采用溶胶-凝胶技术在玻璃衬底上制备了ZnO薄膜和ZnO-SiO₂复合膜.原子力显微镜照片显示ZnO薄膜具有球状纳米晶粒;可见光-紫外透射光谱表明ZnO-SiO₂复合膜在可见光区的透过率大约是85%,透过率从330 nm开始下降,到290 nm附近降为零.由于量子效应,吸收边出现明显的蓝移.在室温下用不同波长的光激发ZnO-SiO₂复合膜,光致发光谱显示ZnO-SiO₂复合膜对应于激子发射的290 nm附近的紫外发光峰与透射谱所显示的吸收边位置一致,没有出现斯托克斯红移.同时,ZnO-SiO₂复合膜出现了双光子和三光子吸收现象和上转换发光现象. 关键词： 2')" href="#">ZnO-SiO₂ 量子效应 双光子和三光子吸收 上转换发光     

Substrate effects on the oxygen gas sensing properties of SnO2/TiO2 thin films

In this study, SnO₂/TiO₂ thin films are fabricated on SiO₂/Si and Corning glass 1737 substrates using a R.F. magnetron sputtering process. The gas sensing properties of these films under an oxygen atmosphere with and without UV irradiation are carefully examined. The surface structure, morphology, optical transmission characteristics, and chemical compositions of the films are analyzed by atomic force microscopy, scanning electron microscopy and PL spectrometry. It is found that the oxygen sensitivity of the films deposited on Corning glass 1737 substrates is significantly lower than that of the films grown on SiO₂/Si substrates. Therefore, the results suggest that SiO₂/Si is an appropriate substrate material for oxygen gas sensors fabricated using thin SnO₂/TiO₂ films.     

衬底对原位氧化制备的ZnO薄膜结构和光学性质的影响

 采用射频反应溅射法在不同衬底上制备Zn₃N₂薄膜,然后对其原位氧化制备ZnO薄膜。利用X射线衍射分析(XRD)、扫描电子显微镜(SEM)和光致发光谱(PL)等表征技术研究了不同衬底对ZnO薄膜的结晶特性和发光性能的影响。XRD研究结果显示:Zn₃N₂薄膜在500 ℃原位氧化3 h后完全转变为ZnO薄膜,在玻璃和熔融石英衬底上制备的多晶ZnO薄膜无择优取向,而单晶硅（100）衬底上的多晶ZnO薄膜具有较好的沿（002）方向的择优取向。PL测试结果显示:硅和熔融石英衬底上的多晶ZnO薄膜发光性能良好,激子复合产生的紫外发光峰很强,且半高宽较窄,而来自于深能级发射的绿色发光峰很弱;而玻璃衬底上的多晶ZnO薄膜发光性能较差。     

连续激光辐照下二氧化钒薄膜热致相变实验研究

 介绍了VO₂薄膜的相变原理，用磁控离子溅射法制备了VO₂薄膜，并进行了X射线衍射和不同温度下的光谱透过率测量。在1.319 μm 连续波激光辐照下，实时测量了VO₂薄膜的温度变化，以及由于温度变化引起相变后对激光透过率的变化。结果表明，入射到薄膜表面的平均功率为8.9 W、光斑直径2 mm时，激光出光480 ms后，VO₂的温度从室温上升到约100 ℃，薄膜发生了相变，其对1.319 μm激光的透过率从相变前的48％降为相变后的28％。