溶胶-凝胶VO2薄膜转换特性研究

利用溶胶凝胶法在SiO2Si衬底上沉积高取向的V2O5薄膜,在压强低于2Pa,温度高于400℃的条件下,对V2O5薄膜进行真空烘烤,获得了电阻率变化3个数量级以上、弛豫宽度为62℃的VO2多晶薄膜.以X射线衍射(XRD)、扫描电子显微镜(SEM)图和电阻率转换特性等实验结果为依据,详细分析了溶胶凝胶薄膜在真空烘烤时从V2O5向VO2的转化,它经历了从VnO2n+1(n=2,3,4,6)到VO2的过程.实验证明,根据选择合适的成膜热处理条件和真空烘烤条件是实现溶胶凝胶V2O5结构向VO2结构成功转换的关键 关键词： 溶胶-凝胶法 氧化钒薄膜 VO2膜转换特性     

溶胶-凝胶法制备Si基ZnO薄膜的光伏特性

用溶胶-凝胶法在P型半导体Si（100）基片上生长了具有六角晶形的ZnO薄膜。SEM和XRD显示,C轴择优取向性明显,薄膜生长质量较好。ZnO薄膜的光致发光谱不仅有384.2nm的紫外波峰（FWHM=20.3nm）,而且还有649.2nm的红光波峰（FWHM=214nm）,两峰相对高度比为0.934。用波长为632.8nm的氦氖激光照射ZnO薄膜的表面,产生了明显的光伏效应。     

快速热处理制备相变氧化钒薄膜及其特性研究

采用直流对靶磁控溅射在Si<100>基底上沉积金属V薄膜, 然后分别在纯氧气环境和纯氮气环境下进行快速热处理制备具有 金属-半导体相变特性的氧化钒(VO_X)薄膜, 热处理条件分别为纯氧气环境下430℃/40 s, 450℃/40 s, 470℃/40 s, 450℃/30 s, 450℃/50 s, 纯氮气环境下500℃/15 s. 用X射线衍射仪、X射线光电子能谱、原子力显微镜 和扫描电子显微镜对薄膜的结晶结构、钒的价态和组分以及微观形貌进行分析. 利用四探针薄膜电阻测量方法和THz时域频谱技术分析薄膜的电学特性和光学特性. 结果表明: 金属V薄膜经过纯氧气环境450℃/40 s快速热处理 后形成了具有低相变特性的VO_X薄膜, 升温前后薄膜方块电阻变化幅度达到两个数量级, THz透射强度变化幅度较小. 为了提高薄膜的相变特性, 对制备的VO_X薄膜采用纯氮气环境500℃/15 s快速热处理, 薄膜的相变特性有了明显提升, 相变前后方块电阻变化达到3个数量级, THz透射强度变化达到56.33%.     

直流磁控溅射制备氧化钒薄膜

讨论了在低温下以高纯金属钒作靶材,用直流磁控溅射的方法制备出了氧化钒薄膜。通过设计正交试验,分析了氩气和氧气的流量比,溅射功率,工作压强,基底温度对氧化钒薄膜沉积速率和电阻温度系数TCR的影响,采用RTP-500型快速热处理机对氧化钒薄膜样品进行了退火热处理,实验结果表明:当Ar与O2的比例为100:4,溅射功率为120W,工作压强为2Pa时,所获得薄膜TCR较大,都在-2%/K附近,最高的可达-3.6%/K。     

溶胶-凝胶法制备发光薄膜现状

发光薄膜在对比度、分辨率、热传导、均匀性、与基底的附着性、释气速率等方面都显示出较强的优越性,在平板显示领域具有很好的应用背景。本文结合我们的工作综述了通过溶胶－凝胶工艺制备发光薄膜的基本过程、薄膜的表征方法、发光薄膜的当前发展及应用情况。依据组成特点,溶胶－凝胶法制备的发光薄膜可分为无机发光薄膜和有机／无机杂化发光薄膜,它们的光致发光、阴极射线发光、场发射发光和电致发光等性质都已被广泛研究。我们除了采用硅酸酯为主要原料制备了一些硅酸盐基发光薄膜外,还以无机盐为主要原料通过Pechini溶胶－凝胶法制备了稀土离子掺杂的钒酸盐发生薄膜,并结合毛细管微模板技术实现了发光薄膜的图案化。最后,我们对未来溶胶－凝胶法制备发光薄膜的发展及应用情况进行了展望。     

溶胶-凝胶-蒸镀法制备高性能FTO薄膜

以SnCl_4·5H_2O为锡源,SnF_2为氟源,采用溶胶-凝胶-蒸镀法制备F掺杂的SnO_2透明导电氧化物薄膜(FTO薄膜).通过正交实验研究确定最佳反应温度、反应时间和蒸镀温度等制备条件.主要研究元素F的掺杂和膜的结构对FTO薄膜性能的影响,并采用傅里叶变换红外光谱仪、热重-差热分析、X射线衍射、高分辨透射电子显微镜和扫描电子显微镜等进行样品的性能表征.研究结果表明,当反应温度50?C、反应时间5 h、烧结(蒸镀)温度600?C、镀膜次数1次、而F/Sn=14 mol%时,FTO薄膜性能指数ΦTC最大,综合光电性能最优,表面电阻为14.7?·cm-1,平均透光率为74.4%.FTO薄膜内颗粒的平均粒径为20 nm,呈四方金红石型结构,F的掺入替代了部分的O,形成了SnO_(2-x)F_x晶体结构.F的掺杂量是影响FTO薄膜的主要因素,F过多或过少均不利于SnO_(2-x)F_x晶体的生长;FTO薄膜的结构、颗粒形状、大小等三维信息也是影响薄膜性能的因素,主要表现为分形维数越小,薄膜表面越平整,势垒越低,导电性能越好.     

Fe掺杂对溶胶凝胶法制备的ZnO: Ni薄膜结构及发光特性的影响

采用溶胶凝胶法在玻璃基片上制备了ZnO及Ni, Fe共掺杂的Zn_0.95-xNi_0.05Fe_xO (x=0, 0.005, 0.01, 0.03, 0.05) 薄膜. 通过扫描电镜(SEM) 和X射线衍射(XRD) 研究了薄膜样品的表面形貌和晶体结构. 结果表明所有样品都具有(002) 择优取向, Fe掺杂导致ZnO: Ni薄膜的晶体质量变差, 晶粒尺寸减小, 但适当的Fe掺杂有利于获得致密、 均匀的薄膜. XPS测试结果表明样品中Ni离子的价态为+2价, Fe离子的价态为+2价和+3价.室温光致发光(PL) 测量表明, 所有样品均观察到较强的紫外发光峰, 蓝光双峰和绿光发光峰. ZnO: Ni薄膜的发光强度可以通过Fe掺杂进行有效调节. 进而我们讨论了Ni, Fe共掺杂ZnO样品的发光机理.     

溶胶凝胶方法制备纳米氧化钌的超电容特性

采用溶胶凝胶方法制备了具有纳米尺度和多孔特征的氧化钌超电容器活性材料,探讨了烧结温度对电极材料的晶体结构,颗粒大小及电化学特性的影响．结合热失重分析、扫描电镜、循环伏安测试等方法探讨了溶胶凝胶法制备钌产物的组成及在高温条件下发生的分解过程和相应产物．钌氧化物材料经过210℃烧结处理后具有541 F／g的电化学容量,由其组成的超电容器具有67 J/g的能量密度．采用高导电乙炔黑作为载体制备了氧化钌／乙炔黑复合电极材料,当乙炔黑含量为10％时,电极材料的比容量达到802 F/g,采用该电极材料组成的电化学电容器具有100 J／g的能量密度且表现了良好的高功率放电特性．     

GaN薄膜的溶胶-凝胶法制备及其表征

采用溶胶凝胶法成功地制备出氮化镓薄膜.以单质镓为镓源制备镓盐溶液、柠檬酸为络合剂制备出前驱体溶胶,再甩胶于Si(111) 衬底上,在氨气氛下热处理制备出GaN薄膜.X射线衍射（XRD）分析及选区衍射分析（SAED）表明所制备的薄膜是六角纤锌矿结构GaN薄膜;XPS分析其表面,结果显示样品中的镓元素、氮元素均以化合态存在,且Ga：N约为1：1;PL谱分析结果表明所制备的薄膜具有优良的发光性能.     

氧化钒薄膜的微结构及阻变特性研究

采用射频反应溅射法于室温下在Cu/Ti/SiO₂/Si基底上制备了氧化钒薄膜. X-射线衍射、X射线光电子能谱分析仪及原子力显微镜结果表明, 室温下制备的氧化钒薄膜除微弱的V₂O₅ (101)和V₂O₃ (110)峰外, 没有明显的结晶取向, 是VO₂, V₂O₅, V₂O₃及VO的混合相薄膜, 且薄膜表面颗粒大小均匀, 表面均方根粗糙度约为1 nm. 采用半导体参数分析仪对薄膜的电开关特性进行测试. 结果表明薄膜具有较低的开关电压(V_Set<1 V, V_Reset<-0.5 V), 并且具有稳定的可逆开关特性. 薄膜从低阻态转变为高阻态的电流(I_Reset)随限流的增大而增大.通过高低阻态时I-V对数曲线的拟合(高阻态斜率>1, 低阻态斜率=1), 认为Cu离子在薄膜中扩散形成的导电细丝是该体系发生电阻转变的主要机制. 关键词： 氧化钒薄膜 电阻开关 电阻式非挥发存储器 导电细丝     

氧化法结合快速热处理制备VOx薄膜及其性质研究

采用磁控溅射法在单晶Si〈100〉基底上沉积金属钒(V)薄膜,在高纯氧环境下快速热处理制备具有相变特性的氧化钒(VOx)薄膜.利用X射线衍射仪、X射线光电子能谱和扫描电子显微镜对薄膜结晶结构、薄膜中V的价态与组分及表面微观形貌进行分析,应用四探针测试方法和太赫兹时域频谱技术对样品的电学和光学特性进行测试.结果表明:在一定范围的快速热处理保温温度和保温时间下,都可以制备出具有热致相变特性的氧化钒薄膜,相变前后薄膜的方块电阻变化超过两个数量级,薄膜成分主要由V2O5和VO2混合组成,薄膜中V整体价态不因热处理条件改变而不同.在快速热处理条件范围内,500℃ 25 s左右条件下(中温区)制备出的氧化钒薄膜相变特性最佳,并且对THz波有一定的调制作用.     

纳秒激光作用下二氧化钒薄膜相变特性

采用脉冲激光沉积法制备了VO2薄膜,应用X射线衍射和X射线光电子能谱分析表明样品为多晶薄膜。采用泵浦-探针方法研究了二氧化钒薄膜的相变特性,实验结果表明当激光重复频率为160 Hz时,样品最小相变响应为12 ns,相变恢复时间与激光能量按照自然指数关系变化。仿真结果表明当激光能量一定时,二氧化钒薄膜相变恢复时间与衬底材料的热导率、热扩散系数有关。     

A study of the optical properties of titanium oxide films prepared by dc reactive magnetron sputtering

TiO₂ thin films were deposited on the glass substrates by dc reactive magnetron sputtering technique at different sputtering pressures (2 × 10⁻³ to 2 × 10⁻² mbar). The films prepared at low pressures have an anatase phase, and the films prepared at high pressures have an amorphous phase. The optical properties were studied by measuring the transmittance and the ellipsometric spectra. The optical constants of the films in the visible range were obtained by fitting the transmittance combined with the ellipsometry measurements using the classical model with one oscillator. The refractive index of the films decreases from 2.5 until 2.1 as the sputtering pressure increases from 2 × 10⁻³ to 2 × 10⁻² mbar. The films prepared at the pressure higher than 6 × 10⁻³ mbar show a volume inhomogeneity. This volume inhomogeneity has been calculated by fitting the transmittance and the ellipsometric spectra. The volume inhomogeneity of the film prepared at the highest sputtering pressure is about 10%. Although the films prepared at high pressures show a large volume inhomogeneity, they have low extinction coefficients. It is suggested that the anatase phase results in more light scattering than amorphous phase does, and then a high extinction coefficient.     

Surface oxidation of vanadium dioxide films prepared by radio frequency magnetron sputtering

This paper reports that the thermochromic vanadium dioxide films were deposited on various transparent substrates by radio frequency magnetron sputtering, and then aged under circumstance for years. Samples were characterized with several different techniques such as x-ray diffraction, x-ray photoelectron spectroscopy, and Raman, when they were fresh from sputter chamber and aged after years, respectively, in order to determine their structure and composition. It finds that a small amount of sodium occurred on the surface of vanadium dioxide films, which was probably due to sodium ion diffusion from soda-lime glass when sputtering was performed at high substrate temperature. It also finds that aging for years significantly affected the nonstoichiometry of vanadium dioxide films, thus inducing much change in Raman modes.     

Some properties of indium-tin oxide films

Thin films of indium-tin oxide have been deposited by DC diode sputtering from an indium-tin alloy target in an argon, hydrogen and oxygen atmosphere. Films with sheet resistance of 11 ohms/square and 80% light transmission have been obtained. The effect of cathode composition and gas mixture on sheet resistance and optical transmission properties of the films have been studied.     

溶胶-凝胶法制备ZnO薄膜的成核-生长和失稳分解研究

采用溶胶-凝胶法在ZnWO₄单晶上制备出透明的ZnO薄膜.通过光学显微镜观察了Z nO薄膜的表面形貌.实验结果表明，ZnO薄膜的形成经历了表面成核，晶粒长大和岛的形成三 个不同的阶段.由于ZnO晶核是在非平衡条件下生长的，在生长过程中不可避免地出现了枝晶 生长和分形生长以及失稳分解. 关键词： 氧化锌薄膜 成核 枝晶生长 分形生长 失稳分解     

The microstructures and electrical properties of Y-doped amorphous vanadium oxide thin films

One of promising approaches for further improving the sensitivity of microbolometer arrays with greatly-reduced pixel size is using the thermal-sensitive materials with higher performance. In this paper, Y-doped vanadium oxide (VO_x) thin films prepared by a reactively sputtering process exhibit enhanced performance for the microbolometer application compared with frequently-applied VO_x thin films. Both undoped and Y-doped VO_x thin films are amorphous due to the relatively low deposition temperature. Y-doped VO_x thin films exhibit smoother surface morphology than VO_x due to the restrained expansion of particles during depositions. Y-doping increases the temperature coefficient of resistivity by over 20% for the doping level of 1.30 at%. The change rate of resistivity, after aging for 72 h, of thin films was reduced from about 15% for undoped VO_x to 2% due to the introduction of Y. Moreover, Y-doped VO_x thin films have a low 1/f noise level as VO_x ones. Y-doping provides an attractive approach for preparing VO_x thermal-sensitive materials with enhanced performance for microbolometers.     

Effects of thermal annealing on titanium oxide films prepared by ion-assisted deposition

Titanium oxide thin films are prepared at a substrate temperature of 250 °C by electron-beam evaporation and ionassisted deposition. The effects of thermal annealing temperatures from 100 to 450 °C on the optical and mechanical properties are studied. The optical and mechanical properties include refractive indices, extinction coefficients, residual stress, surface roughness and crystallization. Experimental results show these properties of titanium oxide films clearly depend on the thermal annealing process.     

Effects of oxygen content on the microstructures and optical properties of thermochromic vanadium oxide thin films

Reactive direct current magnetron sputtering and in situ thermal oxidation were used to prepare vanadium oxide (VO _X ) thin films with different oxygen contents. X-ray diffraction, Fourier transform infrared spectroscopy and a field emission scanning electron microscope were employed to characterize the films. The optical properties of the VO _X films at room temperature and 90 °C were investigated by applying an spectroscopic ellipsometer with a three-layer model of BEMA/Brendel–Bormann oscillator/substrate. It was demonstrated that the vanadium–oxygen bonds were strengthened, the film thickness and roughness decreased, while the grain size increased with increasing oxygen content. The increase in oxygen content had the effect of decreasing the near-infrared reflectance and free-electron concentration of the film at 90°C due to the decrease in the amount of VO₂.     

氧化钒薄膜微观结构的研究

采用直流磁控反应溅射在Si(100)衬底上溅射得到(001)取向的V₂O₅薄膜.x射线衍射(XRD)、扫描电镜(SEM)和傅里叶变换红外光谱(FTIR)的结果表明，氧分压影响薄膜的成分和生长取向，在氧分压0.4Pa时溅射得到(001)取向的纳米V₂O₅薄膜，即沿c轴垂直衬底方向取向生长的薄膜.V₂O₅薄膜经过真空退火得到(001)取向的VO₂薄膜，晶体颗 关键词： 微观结构 氧化钒薄膜 择优取向 直流磁控溅射