紫外光照下金属氧化物薄膜气敏特性研究进展

介绍了近期文献中对紫外光照下半导体金属氧化物薄膜气敏特性的研究结果:紫外光照引起SnO2,In2O3,ZnO薄膜电导显著增大;提高室温下薄膜对CO,NO2气体检测的灵敏度,减少响应和恢复时间;介绍了一种对紫外光增强气敏机制的物理模型分析方法。最后讨论了当前存在的难点问题(室温下气体检测的灵敏度不高及使用紫外光源不便)及未来研究方向(借改变薄膜的制备方法、工艺条件、优化金属氧化物薄膜的结构;通过掺杂复合改变薄膜的成分以及寻找禁带宽度窄的半导体材料等)。     

SAW氢传感器敏感薄膜的研究进展

氢敏薄膜的性质对SAW氢传感器的性能起着至关重要的作用。综述了SAW氢传感器敏感薄膜的国内外研究进展,比较了金属型和金属氧化物半导体(MOS)型薄膜材料的特点,着重阐述了金属氧化物半导体薄膜对SAW的作用机理和改性途径,以及纳米技术在SAW氢传感器敏感薄膜中的应用,展望了氢敏薄膜的发展方向。     

其它材料

SPIE-Vol.4086 0224453SPIE 会议录,卷4086:薄膜物理与应用=Proceedingsof SPIE,Vol.4086:Thin film physics and applications[会,英]/Chinese Physical Society.—887P.(E)本会议录收集了在上海召开的薄膜物理与应用会议上发表的200篇论文,内容涉及半导体薄膜,金属薄膜,金属氧化物薄膜,磁性薄膜超导体薄膜,绝缘体薄     

衬底温度对纳米晶SnO_2薄膜结晶特性的影响

阐述了金属氧化物SnO2纳米薄膜研究的发展情况及其应用前景,介绍了采用磁控溅射技术,使用混合气体Ar和O2,在衬底温度为150～400℃的耐热玻璃基片上制备了纳米晶SnO2∶Sb透明导电薄膜。通过测定x射线衍射谱,表明薄膜择优取向为[110]和[211]方向,SnO2∶Sb薄膜的结晶特性随衬底温度变化。     

椭偏技术的原理及其在功能薄膜表征中的应用

随着计算机技术的不断发展，已有一百多年历史的椭偏技术的研究重点已从该技术本身转移到了它在材料分析中的新用途。通过介绍椭偏技术的测量原理，给出了椭偏仪在材料表征中的应用范围和局限。研究表明，结合其他分析工具并建立精细的椭偏模型，可变入射角光谱椭偏仪（ＶＡＳＥ）能定量测量各种功能金属氧化物薄膜的厚度、光学常数和气孔率。ＶＡＳＥ将在功能金属氧化物外延薄膜的生长控制和性能优化等方面发挥积极的作用。     

多功能ABO3型金属氧化物薄膜及其水热法和电化学—水热法合成

功能陶瓷薄膜化技术的飞速发展给新颖功能器件的研究和开展带来了巨大活力。本文回顾了复杂金属氧化物薄膜的制备技术，着重介绍了最新发展起来的低温氧化物薄膜工艺：水热法和电化学－水热法，并对水热反应沉膜机理作了分析。     

不同衬底温度生长的La_(0.5)Sr_(0.5)CoO_3薄膜椭圆偏振光谱研究

采用脉冲激光沉积法(PLD)在不同Si(100)衬底温度下制备了La_(0.5)Sr_(0.5)CoO_3(LSCO)导电金属氧化物薄膜.X射线衍射(XRD)分析表明,随着衬底温度升高LSCO薄膜的结晶质量增加,在650℃和700℃下制备的薄膜是具有单一钙钛矿结构的多晶薄膜.通过椭圆偏振光谱仪测量了400～1100nm波长范围内该导电金属氧化物薄膜的光学性质,采用双Lorentz振子色散关系及三相结构模型(Air/LSCO/Si)拟合获得了薄膜的光学常数.结果表明,薄膜的折射率随着衬底温度的升高而减小,然而在可见-近红外波长范围内消光系数随着衬底温度的升高而增大.这主要与薄膜的晶化质量和导电性能有密切的关系.     

应用材料公司推出先进化学气相淀积薄膜技术

在日前举办的SEMICONChina上,应用材料公司向业界展示了全新等离子体增强化学气相淀积（PECVD）薄膜技术,用于制造适用于下一代平板电脑和电视的更高性能高分辨率显示。这些源自应用材料公司业界领先的AKT—PECVD系统的先进绝缘薄膜,使得基于金属氧化物的晶体管的应用成为可能,制造出尺寸更小、开关速度更快的像素,从而帮助客户推出更受消费者欢迎的高分辨率显示屏。     

功能电子陶瓷的MOCVD薄膜技术

与常用电子陶瓷薄膜技术相比,ＭＯＣＶＤ技术具有薄膜化学成分、结晶结构和氧化程度易控制,沉积温度低,沉积速率高,薄膜的致密性、均匀性和台阶覆盖性好,可理想生长多组元和多层结构的功能金属氧化物薄膜,能直接由实验室转入规模生产及与硅的大规模集成工艺兼容等优点。应用自制设备及ＭＯＣＶＤ技术,分别在高掺杂硅片和有透明导电膜玻璃的基片上生长了ＴｉＯ２薄膜。测得的１ｍｍＡｕ圆点／ＴｉＯ２薄膜／ｐ＋－Ｓｉ衬底样品的Ｉ－Ｖ和Ｃ－Ｖ特性,清楚地给出了ＭＩＳ结构的行为。淀积在透明导电膜玻璃上的ＴｉＯ２薄膜有电致变色现象。     

LaNiO3薄膜热稳定性的研究

LaNiO3导电金属氧化物薄膜在现代应用科学研究中作为电极和过渡阻挡层倍受青睐，它具有很好的导电特性和稳定性。该文采用射频溅射法制备了具有(100)择优取向的赝立方结构LaNiO3-x薄膜，并进行了原位热处理。实验结果表明，在265℃的处理条件下，LaNiO3薄膜表现出不稳定性，晶格中的氧在2h内失去了2.7％。氧的损失对品格结构没有明显影响，但薄膜的导电性能明显下降，折射率和消光系数也具有相同幅度的下降。对薄膜的应用具有一定的影响。该文从LaNiO3薄膜的导电机理方面对实验现象给出了分析和解释。     

Thermochemical action of laser radiation on thin metal films

Laser-activated oxidation of thin metal films by the action of pulsed laser radiation is investigated theoretically and experimentally. A physical and mathematical model based on the Cabrera-Mott oxidation theory is developed. The basic relations, describing the process, are obtained numerically. Four different experimental methods have been used to examine qualitatively and quantitatively the laser-activated oxidation. The results obtained show that pulsed laser irradiation of thin metal films in the oxidizing environment may cause buildup of the thin oxide layer, which is very stable and may be used as a masking layer in the laser lithography. Comparison between experimental and theoretical results shows that the developed theoretical model describes the oxidation process well, and it may be used to find the optimum conditions for the thermochemical laser treatment of thin metal films.     

Time–Temperature–Transformation (TTT) Diagrams for Crystallization of Metal Oxide Thin Films

Time–temperature–transformation (TTT) diagrams are proposed for the crystallization of amorphous metal oxide thin films and their specific characteristics are discussed in comparison to glass‐based materials, such as glass‐ceramics and metallic glasses. The films crystallize from amorphous to full crystallinity in the solid state. As an example the crystallization kinetics for a single‐phase metal oxide, ceria, and its gadolinia solid solutions are reported made by the precipitation thin‐film method spray pyrolysis. The crystallization of an amorphous metal oxide thin film generally follows the Lijschitz–Sletow–Wagner (LSW) Ostwald ripening theory: Below the percolation threshold of 20 vol% single grains crystallize in the amorphous phase and low crystallization rates are measured. In this state no impact of solute on crystallization is measurable. Once the grains form primary clusters above the threshold the solute slows down crystallization (and grain growth) thus shifting the TTT curves of the doped ceria films to longer times and higher temperatures in comparison to undoped ceria. Current views on crystallization of metal oxide thin films, the impact of solute dragging, and primary TTT diagrams are discussed. Finally, examples on how to use these TTT diagrams for better thermokinetic engineering of metal oxide thin films for MEMS are given, for example, for micro‐Solid Oxide Fuel Cells and resistive sensors. In these examples the electrical properties depend on the degree of crystallinity and, thereby, on the TTT conditions.     

Rigorous optical modeling and optimization of thin‐film photovoltaic cells with textured transparent conductive oxides

Typical thin‐film photovoltaic (PV) cells incorporate a textured transparent conductive oxide to enhance light trapping and efficiently harvest solar energy. Rigorous coherent optical simulations of these devices and a complete characterization of these textured films are a challenging problem because of the several orders of magnitude difference between the wavelengths of interest and the spatial dimension of the sample that needs to be evaluated. In this paper, a practical approach for rigorous and predictive modeling of optical properties of thin‐film PV cells incorporating a vast variety of light‐trapping structures including semi‐coherent textured films and patterned coherent structures is presented. In contrast to the existing semi‐empirical device models, it is demonstrated that the presented methodology can accurately predict the scattering properties of textured fluorine‐doped tin oxide and aluminum‐doped zinc oxide conductive transparent films. It is further shown that the optical response of single‐junction and tandem‐junction PV devices incorporating such films can also be predicted with good accuracy as compared with the measured results. Next, a methodology to identify the sufficient statistical fingerprints of semi‐coherent textured films that are needed to unambiguously predict the light propagation in thin‐film cells is presented. This comprehensive approach then lends itself to identifying the optimal surface morphology needed for strong light trapping. This rigorous approach automatically includes the effects of important loss mechanisms such as the surface plasmon‐enhanced absorption in textured metal surfaces that are otherwise very difficult to account for semi‐coherent approaches based on scalar scattering theory. Copyright © 2011 John Wiley & Sons, Ltd.     

Gas Selective Ultrathin Organic Covalent Networks Synthesized by iPECVD: Does the Central Metal Ion Matter?

The potential of porphyrin‐derived metal organic covalent networks (OCN) thin films on light gas separations has been recently demonstrated. However, whether or not the central metal ion of the porphyrin plays a key role on separation performance has yet to be elucidated. Here, one metal‐free and three metal‐containing (zinc(II), manganese(III), and cobalt(II)) porphyrin‐derived OCN thin films are successfully deposited on various substrates via an easily scalable initiated plasma‐enhanced chemical vapor deposition approach. Among these four porphyrin‐derived OCN thin films exhibiting superior light gas separation performances, three of them are synthesized for the first time. The gas permeation properties of these four OCN thin films suggest that the central metal ions neither significantly alter the packing structure of resulting OCN thin films, nor introduce facilitated transport phenomena favoring oxygen transmission. This observation is further validated by density functional theory calculations. Additional aging tests are also carried out to evaluate the physical aging behavior of the OCN thin films.     

金属离子掺杂纳米TiO2薄膜光阳极的性能研究

采用溶胶-凝胶法在玻璃衬底上制备TiO2多孔薄膜,掺杂不同功函数的金属离子制备M-TiO2纳米薄膜电极,XRD、AFM,UV-Vis检测M-TiO2结构、形貌和性能.结果表明:掺杂摩尔分数2%的金属离子没有改变TiO2的晶格结构,但其吸收峰在可见光区都发生明显的红移,禁带宽度降低,掺杂后的M-TiO2电极比没有掺杂的T...     

氧化钒薄膜光伏效应机理分析

氧化钒薄膜是非致冷红外焦平面探测器的重要组成部分,光电特性一直是国内外的研究热点.用反应磁控溅射方法在K9玻璃衬底上制备了氧化钒薄膜,并在特定条件下对其进行了退火处理.结果发现,在300℃下退火180 s的氧化钒薄膜在可见光照射情况下呈现出了光伏效应,这说明光生载流子在氧化钒薄膜表层形成后得到了有效分离.该光伏特性为氧...     

Investigation of the electrical transport mechanism in VOx thin films

Vanadium oxide VO₂ is a material that transforms from semiconductor to a metal state at a temperature of 67 °C. This phase transformation is accompanied by a dramatic change in its electrical and optical properties. Therefore, vanadium oxide thin films are most attractive for switching applications. Non-stoichiometric thin films of VO_x, including VO₂, also present such thermal response.This paper presents the optical and electrical properties of vanadium oxide thin films deposited by vacuum thermal evaporation of a metal vanadium with follows oxidation. We have studied the electro-physical behavior of these films during their phase transition. It was shown that the electrical transport mechanism of the obtained vanadium oxide films differ in low and high electrical fields. In low electrical fields, conductivity is obtained by the Schottky transport mechanism, whereas in high electrical fields, conductivity ranges from Ohmic, for medium fields, to Poole-Frenkel for higher fields. Also, FTIR and near IR reflectance characteristics of the obtained films are presented.     

Accelerated degradation of Al3+ doped ZnO thin films using damp heat test

Two different types of aluminum-doped zinc oxide (AZO) thin films were fabricated using low cost sol–gel technique. By applying damp heat testing, the optical and electrical properties of those films were investigated under the influence of accelerated degradation from moisture or moisture vapor. Complementary measurements of optical transmittance, work function, and conductivity allowed exploring the degradation of AZO thin films and the corresponding OPV devices. We found that optical properties like transmittance, absorption coefficient, and band gap are not influenced by temperature and moisture. However, an increase in the work function, and a decrease in the conductivity of AZO films were observed upon damp heat exposure indicating the formation of a barrier or depletion layer at the metal oxide semiconductor interface.     

Electrical properties of Pb(Zr,Ti)O3 films prepared on ITO glass

Pb(Zr,Ti)O₃ thin films were successfully prepared on a Pt bottom electrode with indium tin oxide coated glass substrates using RF magnetron sputtering. Use of the indium tin oxide coated glass substrate reduced the fatigue characteristics and provided for excellent crystallization of the Pb(Zr,Ti)O₃ thin films. The polarization versus fatigue characteristics showed 10% degradation after 10⁹ cycles. These results indicate that Pt/indium tin oxide double electrodes can be improved both in terms of fatigue and ferroelectric properties through the use of Pb(Zr,Ti)O₃ thin films on glass substrates, resulting in better performance than metal electrodes.