有限元结合纳米压痕法确定ZnO薄膜的压电系数

为准确表征横观各向同性ZnO薄膜材料的压电性能,以沉积在硅基底上的ZnO薄膜为研究对象,结合有限元法和纳米压痕法确定了ZnO薄膜的压电系数.正向分析,用ABAQUS软件的压电模块模拟了纳米压痕实验,分别确定了薄膜压电系数与最大加载力、加载曲线指数之间的无量纲方程.反向分析,对ZnO薄膜/硅基底体系进行纳米压痕实验,将实...     

0.08Pb(Fe1/3Sb2/3)O3-yPbTiO3-(1-0.08-y)PbZrO3压电陶瓷性能研究

合成了钙钛矿结构的0.08Pb(Fe1/3 Sb2/3)O3-yPb-TiO3-(1-0.08-y)PbZrO3三元系压电陶瓷材料,测量并计算了不同y值时的压电常数(d33)、机电耦合系数kp、k33)、机械品质因数(Qm)以及极化前后的介电常数(εT33/ε0),对实验现象进行了简单的讨论,得出一些有益的结论;实验结果表明当选取合适的y值时可以获得压电性能良好的压电材料,如y=0.45时材料的平面机电耦合系数kp、纵向机电耦合系数k33和压电常数d33分别达到0.64×10-12C/N、0.72×10-12C/N和365×10-12C/N.     

硅基三元系PMnN-PZT铁电薄膜制备与研究

利用磁控溅射方法在单晶Si基底上沉积三元系铁电薄膜6%PMnN-94%PZT(6%Pb(Mn1/3,Nb2/3)O3-94%Pb(Zr0.52,Ti0.48)O3),采用淬火方法对薄膜进行处理,以促进薄膜钙钛矿结构形成。同时,在相同条件下制备非掺杂PZT(52/48)薄膜以对比薄膜掺杂效果。运用X射线衍射(XRD)技术分析薄膜晶向及晶体结构,运用Sawyer Tower电路测试薄膜铁电性能,运用激光测振仪测试薄膜的压电系数。实验结果表明,所沉积薄膜为多晶钙钛矿结构铁电薄膜,薄膜铁电剩余极化Pr=23.7μC/cm2,饱和极化Ps=40μC/cm2,矫顽场电压2Ec=139kV/cm,横向压电系数e11=-13.2C/m2,薄膜的铁电及压电性能优良。     

ZnO压电薄膜的生长与应用

本文实验研究了ZnO压电薄膜的生长与表征,运用XRD和SEM测试了磁控溅射生长的ZnO压电薄膜的C轴择优取向生长情况和晶粒质量,比较了Si、覆盖在si基底上的Al薄膜和SixNy薄膜三种材料衬底以及退火处理对ZnO薄膜的结晶质量的影响.还开发了仍然采用Al作为底电极但用一层SixNy薄膜与ZnO层隔离的MEMS压电器件的微制造工艺,以满足生长高质量的ZnO压电薄膜并与CMOS工艺兼容的要求.     

MOCVD制备定向生长ZnO压电薄膜

采用大气开放式金属有机化合物化学气相沉积(A-MOCVD)的方法,在普通多晶黄铜基片上制备ZnO薄膜.薄膜的SEM、XRD结果表明ZnO沿C轴取向垂直生长在基片上.综合分析ZnO自身晶体生长习性,提出了ZnO薄膜在普通多晶铜表面的生长模型.并将ZnO薄膜制备成压电双晶片元件,在光学显微镜下能观察到元件尖端产生了很大的位移量,结果表明高定向性ZnO薄膜具有优异的压电特性.该压电器件使得传统的小变形双晶片元件的数学模型失效,有必要建立新型大变形双晶片物理、数学模型.     

应用于体声波谐振器的ZnO薄膜结构和电学特性

采用直流磁控溅射的方法制备了ZnO压电薄膜,并在双面抛光的熔融石英基片上制备了高次谐波体声波谐振器.x射线衍射结果显示ZnO压电薄膜C轴择优取向明显,衍射峰半高宽为0.1624°,显示出较好的结晶质量;扫描电镜分析观察到ZnO垂直于基片表面的柱形晶粒结构和较平滑的薄膜表面.体声波器件的电学测试结果显示器件具有很好的多模谐振特性,说明ZnO压电薄膜很好地激发出了厚度方向的纵声波,可应用于体声波器件和声表面波器件中.另外采用间接的方法得到ZnO压电薄膜在870MHz时的介电常数约为5.24,介电损耗因子为1.07,进一步减小介电损耗因子,可以提高器件的Q值.     

多孔PTFE/P(VDF-HFP)复合膜的驻极体性质

通过栅控恒压负电晕充电、等温表面电位衰减测量、热刺激放电(Thermally Stimulated Discharge,TSD)电流谱分析、电荷TSD和压电d33系数测量等方法,首次研究了将旋涂在基片上的含一定溶剂的聚偏氟乙烯和六氟丙烯共聚物(P(VDF-HFP))薄膜与多孔聚四氟乙烯薄膜均匀压合形成的多孔PTFE/P(VDF-HFP)双层复合膜系的驻极体性质.从多孔PTFE面充电的双层膜具有较从P(VDF-HFP)面充电优异的多的电荷热稳定性.使用介电谐振谱测量的双层膜的压电d33系数(31pC/N)是传统的铁电聚合物材料PVDF相应值(15 pC/N)的2倍左右.     

N_2流量对HiPIMS制备Al-N共掺杂ZnO薄膜的性能影响

采用高功率脉冲反应磁控溅射(HiPIMS)在玻璃基底上沉积Al-N共掺氧化锌(ZnO)薄膜,研究氮气(N_2)流量对Al-N共掺杂ZnO薄膜的晶体结构、表面形貌和电学性质的影响。测量结果表明,N_2流量对掺杂的ZnO薄膜电导率类型转变和光电性能有很大影响:当N_2流量为8 mL/min时,掺杂ZnO薄膜在可见光波段透过率大于85%,薄膜导电类型为n型;随着N_2流量的增加,薄膜经历n-p-n型的转变过程。当N_2流量为20 mL/min时,掺杂的ZnO结晶性最好,晶体缺陷少、XRD衍射峰半峰宽(FWHM)最小、表面粗糙度也低,为p-ZnO。薄膜电学性能测量显示:载流子浓度、迁移率、电阻率分别为5.47×10~(17)cm~(-3)、2.7 cm~2/Vs、4.51Ωcm。     

PEEK基底上厚度为6.4 nm的金薄膜导热导电性能研究

运用高真空溅射镀膜仪在聚醚醚酮(PEEK)薄膜和纤维表面分别制备了厚度为6. 4 nm的金薄膜,并通过瞬态电热技术(TET)测量了该金薄膜的导热性和导电性。PEEK薄膜基底上厚度为6. 4 nm的金薄膜的导热系数、导电系数和洛伦兹数分别为283. 97 W·m~(-1)·K~(-1)、2. 46×10~7Ω~(-1)·m~(-1)和3. 49×10~(-8)W·Ω·K~(-2)。PEEK纤维基底上厚度为6. 4 nm的金薄膜的导热系数、导电系数和洛伦兹数分别为81. 11 W·m~(-1)·K~(-1)、1. 20×10~7Ω~(-1)·m~(-1)和2. 17×10~(-8)W·Ω·K~(-2)。研究发现,在不同基底材料上制备的金薄膜的导热系数、导电系数和洛伦兹数均不同。这种差异可以归因于以下两点:一方面,不同基底材料上制备的金薄膜的晶粒尺寸不同;另一方面,不同的基底材料会引起基底与金薄膜结合界面的平整度不同。金薄膜晶粒尺寸越小,其电子的导热系数、导电系数越小;金薄膜与基底的结合界面平整度越差,其声子的导热系数越小。     

热处理对溶胶-凝胶法制备ZnO薄膜性能的影响

以(CH3COO)2Zn·2H2O为前驱物,利用溶胶-凝胶旋转涂膜法以普通玻璃为基底制备ZnO薄膜。分别采用X射线衍射仪、紫外-可见分光光度计和扫描电子显微镜等对ZnO薄膜的物相组分、透射率和表面形貌进行测量与表征。研究了热处理温度对ZnO薄膜的物相结构和光学特性的影响。实验结果表明,ZnO薄膜的物相结构和可见光透射率都与热处理温度有关,随着热处理温度升高,ZnO薄膜的晶粒尺寸增大,晶格常数逐渐减小,薄膜的透射率增大。     

Structures, varistor properties, and electrical stability of ZnO thin films

In this letter, we report the structures, varistor properties, and electrical stability of ZnO thin films deposited by the gas discharge activated reaction evaporation (GDARE) technique. The X-ray diffraction (XRD) and atomic force microscopy (AFM) measurements showed that the thin films thus prepared have polycrystalline structures with the preferred orientation along the (002) plane whose surface consists of ZnO aggregates with sizes of 50-200 nm. The ZnO thin films deposited by GDARE and annealed at 250 °C for 2 h have strong nonlinear varistor-type I-V characteristics. The nonlinear coefficient (α) of a single-layered ZnO thin film sample was 33 and that of a triple-layered sample obtained by the many-time deposition was 62. The varistor voltages (V_1mA) of the two samples are found rather close each other. Under a DC bias of 0.75 V_1mA and a temperature of 150 °C these thin films exhibit good electrical stability with a degradation rate coefficient K_T of 0.05 mA/h^1/2.     

Optical characterization of ZnO thin films deposited by Sol-gel method

In this paper, ZnO thin film is deposited on Pt/TiO₂/SiO₂/Si substrate using the sol-gel method and the effect of annealing temperature on the structural morphology and optical properties of ZnO thin films is investigated. The ZnO thin films are crystallized by the heat treatment at over 400°C. The ZnO thin film annealed at 600°C exhibits the greatest c-axis orientation and the Full-Width-Half-Maximum (FWHM) of X-ray peak is 0.4360°. A dense ZnO thin film is deposited by the growth of uniform grains with the increase of annealing temperature but when the annealing temperature increases to 700°C, the surface morphology of ZnO thin film becomes worse by the aggregation of ZnO particles. In the results of surface morphology of ZnO thin film using atomic force microscope (AFM), the surface roughness of ZnO thin film annealed at 600°C is smallest, that is, approximately 1.048 nm. For the PL characteristics of ZnO thin film, it is observed that ZnO thin film annealed at 600°C exhibits the greatest UV (ultraviolet) exciton emission at approximately 378 nm, and the smallest visible emission at approximately 510 nm among ZnO thin films annealed at various temperatures. It is deduced that ZnO thin film annealed at 600°C is formed most stoichiometrically, since the visible emission at approximately 510 nm comes from either oxygen vacancies or impurities.     

Corona poling of highly (001)/(100)-oriented lead zirconate titanate thin films

Corona poling is an interesting non-contact poling process for ferroelectric materials which, has in the past, been extensively applied to ferroelectric polymers, but not to other types of ferroelectric materials. Here, it has been investigated as an alternative technique to the conventional direct-contact poling of ferroelectric thin films.

Contact-poling and corona poling techniques were applied to highly (001)/(100) oriented lead zirconate titanate thin films of composition 52% Zr, 48% Ti (PZT52/48). Different poling voltages and durations were used to pole the samples, and the effects on the piezoelectric coefficients e_31,f and d_33,f were explored. From the magnitudes of piezoelectric coefficients and suppression of e_31,f relative to d_33,f, it was concluded that corona poling is a more suitable technique for poling PZT52/48 thin films than direct poling, since piezoelectric coefficients were higher and sample damage was less for corona poling when compared with contact-poling.     

Effect of the oxygen pressure on the photoluminescence properties of ZnO thin films by PLD

ZnO thin films on Si(111) substrate were deposited by laser ablation of Zn target in oxygen reactive atmosphere; Nd-YAG laser with wavelength of 1064 nm was used as laser source. The experiments were performed at laser energy density of 31 J/cm², substrate temperature of 400 °C and various oxygen pressures (5–65 Pa). X-ray diffraction was applied to characterize the structure of the deposited ZnO films and the optical properties of the ZnO thin films were characterized by photoluminescence with an Ar ion laser as a light source using an excitation wavelength of 325 nm. The influence of the oxygen pressure on the structural and optical properties of ZnO thin films was investigated. It was found that ZnO film with random growth grains can be obtained under the condition of oxygen pressure 5–65 Pa. It will be clearly shown that the grain size and the formation of intrinsic defects depend on the oxygen partial pressure and that high optical quality of the ZnO films is obtained under low oxygen pressure (5 Pa, 11 Pa) conditions.     

Enhancement of crystallinity and optical properties of bilayer TiO2/ZnO thin films prepared by atomic layer deposition

Bilayer and multilayer thin films are becoming increasingly important in the development of faster, smaller and more efficient electronic and optoelectronic devices. One of the motivations of applying bilayer or multilayer structures is to modify the optical properties of materials. Atomic layer deposition (ALD) is a variant of Chemical Vapour Deposition that can produce uniform and conformal thin films with well controlled nanostructures. In this study, we have demonstrated new findings of the use of ALD fabricated bilayer TiO2/ZnO thin films with enhanced crystallinity and optical properties. TiO2 films have been deposited at 300 degrees C for 1000 (51 nm in thickness) or 3000 (161 nm in thickness) deposition cycles onto glass and Si substrates. ZnO films are subsequently deposited on the TiO2 layers at 280 degrees C for 500 deposition cycles (55 nm). The crystallinity and optical properties of the TiO2/ZnO thin films have been analysed by X-ray diffraction, photoluminescence, UV-Vis spectroscopy, Atomic Force Microscopy and Scanning Electron Microscopy. XRD diffraction pattern confirmed the presence of ZnO with wutrtize crystal structure and TiO2 with anatase structure. It shows that the crystallinity of the TiO2 films has been improved with the deposition of ZnO. The intensity of UV luminescence has increased by almost 30% for TiO2/ZnO bilayer as compared to the single layer TiO2. The possible mechanism for the enhancement of the optical properties of bilayer TiO2/ZnO thin films will be discussed.     

Optical properties of electrochemically deposited ZnO thin films on colloidal crystal film of SiO2 microspheres

The optical properties of electrochemically deposited ZnO thin films on colloidal crystal film of SiO2 microspheres structures were studied. Colloidal crystal film of SiO2 microspheres were self-assembled by evaporation using SiO2 in solution at a constant 0.1 wt%. ZnO in thin films was then electrochemically deposited on to colloidal crystal film of SiO2 microspheres. During electrochemical deposition, the content of Zn(NO3)2 x 6H2O in solution was 5 wt%, and the process's conditions were varied between of 2-4 V and 30-120 s at room temperature, with subsequent heat-treatment between 200 and 400 degrees C. A smooth surface and uniform thickness of 1.8 microm were obtained at 3 V for 90 s. The highest PL peak intensity was obtained in the ZnO thin film heat-treated at 400 degrees C. The double layered ZnO/SiO2 colloidal crystals showed clearly better emission properties than the SiO2/ZnO and ZnO structures.     

Preferential growth of ZnO thin films by the atomic layer deposition technique

Preferred orientation of ZnO thin films deposited by the atomic layer deposition (ALD) technique could be manipulated by deposition temperature. In this work, diethyl zinc (DEZn) and deionized water (H(2)O) were used as a zinc source and oxygen source, respectively. The results demonstrated that (10.0) dominant ZnO thin films were grown in the temperature range of 155-220?°C. The c-axis crystal growth of these films was greatly suppressed. Adhesion of anions (such as fragments of an ethyl group) on the (00.2) polar surface of the ZnO thin film was believed to be responsible for this suppression. In contrast, (00.2) dominant ZnO thin films were obtained between 220 and 300?°C. The preferred orientations of (10.0) and (00.2) of the ZnO thin films were examined by XRD texture analysis. The texture analysis results agreed well with the alignments of ZnO nanowires (NWs) which were grown from these ZnO thin films. In this case, the nanosized crystals of ZnO thin films acted as seeds for the growth of ZnO nanowires (NWs) by chemical vapor deposition (CVD) process. The highly (00.2) textured ZnO thin films deposited at high temperatures, such as 280?°C, contained polycrystals with the c?axis perpendicular to the substrate surface and provided a good template for the growth of vertically aligned ZnO NWs.     

Preparation and optimization of epitaxial growth of transparent ZnO nanotip thin films by hydrothermal method

Zinc oxide (ZnO) nanotip thin films were prepared on ZnO coated nanocrystalline ITO/glass substrates by hydrothermal method. In order to obtain the ZnO nanotip arrays with high aspect ratio, the experimental conditions were optimized. The scanning electron microscope images showed that the surface morphology of ZnO thin films could be easily manipulated by changing the seed layer thickness and growth time. The ZnO nanotip thin films were grown epitaxially on ZnO seed layer coated ITO/glass substrates. The surface morphology of ZnO thin films on ITO/glass substrate changed from nanorods with a flat-top end to nanotips as the growth time was increased from 3 to 15 h. The ZnO thin films prepared under these deposition conditions were highly oriented along (002) direction. The as-prepared sample (15 h) was annealed at different temperatures (30, 100, 150, and 270 degrees C). The surface morphologies of annealed ZnO thin films did not show any remarkable change and the best crystallinity was observed at 100 degrees C. The photoluminescence spectra showed that the near band edge emission shifted to shorter wavelength as the annealing temperature was increased from 30 to 270 degrees C, it was due to the intrinsic stress in the films. This was confirmed by X-ray diffraction analyses. NPB thin films were prepared on ITO/clay and ITO/glass substrates by thermal evaporation method. The electrical properties of Ag/NPB/ITO/Clay showed the Ohmic characteristics (J proportional V(1.0)). The J-V characteristic of Ag/NPB/PMMA/ZnO/ITO/Glass showed good rectification behaviour with a diode-ideality factor of 1.36.     

Enhanced acetone detection using Au doped ZnO thin film sensor

Zinc oxide (ZnO) thin films are prepared using sol–gel method for acetone vapor sensing. Zinc acetate dihydrate (Zn(CH₃COO)₂·2H₂O) was taken as starting material and a stable and homogeneous solution was prepared in ethanol by deliquescing the zinc acetate and distinct amount of monoethanolamine as a stabilizing agent. The prepared solution was then coated on silicon substrates by spin coating method and then annealed at 650 °C for preparing ZnO thin films. The thickness of the film was maintained at 410 nm. The structural, morphological and optical studies were done for the synthesized ZnO thin films. The operating temperature and sensor response is considered to be an important parameter for the gas sensing behavior of any material. Therefore, the present study examined the effect of sensing behavior of 3% v/v gold (Au) doped ZnO thin films as a sensor. The response characteristics of 410 nm ZnO thin film for temperature ranging from 180 to 360 °C were determined for the acetone vapors. The reported study provides a significant development towards acetone sensors, where a very high sensitivity with rapid response and recovery times are reported with lowered optimal operating temperature as compared to bare ZnO nano-chains like structured thin films. In comparison to the bare ZnO thin films giving a response of 63 at an operating temperature of 320 °C, a much better response of 132.3 was observed for the Au doped ZnO thin films at an optimised operating temperature of 280 °C for a concentration of 500 ppm of acetone vapors.     

ZnO/SnO_2,SnO_2/ZnO UPF复合膜的制备及气敏特性研究

用直流气体放电活化反应蒸发沉积技术在普通玻璃基片上制备了ZnO／SnO2及SnO2／ZnO超微粒子（UPF）双层复合薄膜。样品经扫描电子显微镜（SEM）和X射线衍射仪分析，结论为超微粒子的复合薄膜。同时提出了最佳制备工艺。气敏测试结果表明：ZnO／SnO2及SnO2／ZnOUPF复合膜较单层ZnO及SnO2UPF表现出优良的选择性，其灵敏度和最佳工作温度也得到相应的改善。