磁控溅射低温沉积ITO薄膜及其光电特性研究

采用直流反应磁控溅射法低温沉积ITO薄膜,用XRD、SEM和UV—Vis分别表征ITO薄膜的晶体结构、表面形貌及其紫外-可见光吸收谱,研究了氧分压、溅射功率及薄膜厚度等工艺参数对薄膜光电性能的影响,结果表明,氧分压过大时,ITO薄膜中有大量的位错和缺陷,使薄膜的电阻率变大,导电性变差;氧分压过小时,薄膜中将有大量氧空位产生,导致晶格变形,使电阻率增加。随着溅射功率增大,在相同时间内薄膜厚度增加,方块电阻减小,薄膜电阻率降低。随着薄膜厚度增加,制备的薄膜晶体结构相对完整,载流子浓度和迁移率逐渐增大,薄膜电阻率变小,进而对样品的光电性能产生明显影响。     

Low-noise solar-blind photodetectors based on LaAlO3 single crystal with transparent indium-tin-oxide electrode as detection window

The low-noise solar-blind photodetectors of indium-tin-oxide/LaAlO(3)/Ag (ITO/LAO/Ag) have been fabricated based on the properties of LAO bandgap excitation and the transparent conductance of ITO thin film. The ITO thin films are epitaxially grown on LAO wafers as the electrodes and detection windows of the photodetectors. The photodetectors have low noise and excellent electromagnetic shielding. The influence of the thickness of ITO thin films on the responsivity of the photodetectors has been studied. The photocurrent responsivity can reach 10.3 mA/W under the irradiation of 200-220 nm for a photodetector with 5 nm thick ITO film. The noise current is 1 pA order magnitude under the sunlight at midday. The experiment results suggest that ITO/LAO/Ag is one of the promising structures for the solar-blind deep-ultraviolet photodetectors.     

空间太阳电池玻璃盖板表面超薄ITO防静电层的设计及制备工艺

ITO/MgF2复合薄膜既具有较好的表面导电性能又具有较高的透过率,可应用于空间太阳电池玻璃盖板表面。文章主要对ITO/MgF2复合薄膜中表层的超薄ITO薄膜进行了研究。利用TFCalc软件模拟了ITO薄膜厚度对ITO/MgF2复合薄膜光学性能的影响,根据模拟结果采用电子束蒸发法在衬底上依次沉积MgF2薄膜和氧化铟锡(ITO)薄膜,研究了ITO薄膜工艺参数(沉积速率、沉积温度和工作气压)和ITO薄膜厚度对ITO/MgF2复合薄膜光电性能及微观结构的影响。当ITO薄膜沉积速率为0.05nm/s、沉积温度为400℃、工作气压为2.3×10~(-2) Pa、厚度为10nm时,表层ITO薄膜基本连续,其方块电阻(1.94kΩ/)已符合设计需求,ITO/MgF2复合薄膜在可见光区间(400~800nm)的平均透过率达到89.00%。     

Thin film passive solar windows produced by reactive evaporation of In-Sn

The semiconductor indium tin oxide (ITO) when present as a thin film has been shown to be transparent to visible radiation while opaque to IR radiation. Sputtering, chemical vapor deposition and other coating methodologies have been used to prepare ITO thin films. Reactive evaporation is an alternative coating technique, which has as its major advantage technical simplicity. Our prepation of ITO thin films (30–90 nm) for passive solar windows included the reactive evaporation of In-Sn alloys (In-5wt.%Sn, In-10wt.%Sn and In-20wt.%Sn) onto commercial soda-lime glass held between 25 and 300 °C. The reactive evaporation atmosphere consisted of oxygen at partial pressures from 1 × 10^-4 to 1 × 10^-3 Torr in residual nitrogen. In selected instances ultrathin palladium nucleating layers were evaporated onto the glass substrates prior to the deposition of the ITO. This was done in order to minimize initial alloy-glass agglomeration effects, thus decreasing the final overall ITO film thickness while increasing the visible transmission properties. The film's visible and IR spectral transmission properties were examined using ratio recording spectrophotometry. The agglomeration, nucleation and growth phenomena of the films were extensively investigated by transmission electron microscopy. The agglomeration was found to be a function of the film thickness, with increasing agglomeration for thinner films. Surface analysis by scanning Auger microscopy (SAM), electron spectroscopy for chemical analysis (ESCA), scanning electron microscopy and energy-dispersive analysis of X-rays was also extensively carried out to determine our particular film properties. SAM indicated that only indium, tin and oxygen were present. No tungsten from the evaporation filament or elements from the glass were found. ESCA indicated that ITO was indeed present on the surface. Such work definitely indicated that ITO can be prepared by reactive physical vapor deposition and that the resultant films have the properties commonly found in sputtered ITO films.     

WO3电致变色薄膜制备过程中光学膜厚测量监控技术的研究

采用真空电子束蒸发方法制备WO3电致变色薄膜过程中，利用极值法光学膜厚测量技术监控薄膜的光学特性，对不同光学膜厚的WO3薄膜的原始态、着色态和退色态的光谱特性进行了对比分析。测试采用二电极恒电压方法，用分光光度计实时测量透过率的变化。结果证明以ITO玻璃作为比较片，极值法监控薄膜光学膜厚，当反射率达到第一极小值，即透过率达到第一极大值时，WO3薄膜得到最好的综合电致变色特性。     

Thickness of ITO thin film influences on fabricating ZnO nanorods applying for dye-sensitized solar cell

Background and purposeIn order to compare the substrates influence on the properties of ZnO films and nanostructures, in this paper, the ITO substrates with different thicknesses were investigated.MethodITO thin films of different thickness (200 nme500 nm) were deposited on glass substrates by DC sputtering, on which ZnO nanorods were fabricated from as-deposited ZnO films by reducing annealing method.ResultsIt was found that the structural and electrical properties of ITO films were significantly influenced by the ITO film thickness. The roughness of ITO films was increased with increase in thickness. The Hall mobility of ITO films was also increased with the increase of film thickness; in contrast, the resistivity was decreased. The highest Hall mobility of 29.2 cm²/V s and the lowest resistivity of 1.303 × 10⁻⁴ Ω cm were obtained from 500 nm-thick ITO film. The structural properties of ZnO nanorods were significantly influenced by the ITO film thickness. The density of ZnO nanorods gradually decreased with the increase in thickness of ITO film.ConclusionThe overall conversion efficiency of demonstrated dye-sensitized solar cell was 2.11% with a fill factor 0.526, indicating high potential to be used as photoanodes in dye-sensitized solar cell applications.     

ITO透明导电薄膜厚度与光电性能的关系

透明导电薄膜的厚度制约其光电性质。本研究利用磁控溅射技术制备了厚度变化范围为200-1500nm的ITO薄膜,探索了薄膜颜色、可见光透过率、面电阻与膜厚的关系。薄膜颜色随着膜厚的增加呈现有规律的变化,可见光透过率随薄膜厚度的增加而呈现振荡下降趋势,并出现了极大值(紫红色),振荡趋势可用多光束干涉解释;薄膜面电阻随膜厚的增加呈减小趋势,薄膜厚度为1387nm时,面电阻为1.3Ω/□,薄膜最小电阻率为1.8×10-4Ω.cm。文章给出了可以通过选择恰当的薄膜厚度,以尽可能满足透明导电薄膜面电阻、透过率两个相互矛盾的指标。     

FeS2/TiO2复合薄膜光电性能

采用溶液浸渍法在ITO导电玻璃表面的多孔TiO2薄膜上沉积了FeS2薄膜.使用Fe2O3粉末保护裸露在外的ITO导电膜在硫气氛中热处理后,制得了FeS2/TiO2复合薄膜.应用B531/H数显测厚指示表、数字式四探针测试仪、XJCM-8太阳电池测试仪等研究了FeS2/TiO2复合薄膜的厚度、ITO导电玻璃的电阻率以及FeS2/TiO2复合薄膜的光电性能.结果表明：此方法制得的FeS2/TiO2复合薄膜具有良好的光电性能;且ITO导电膜的电阻率变化较小.因而适宜制备色素增感太阳能电池（DSSC）.     

Quality enhancement of AZO thin films at various thicknesses by introducing ITO buffer layer

Due to the simultaneously superior optical transmittance and low electrical resistivity, transparent conductive electrodes play a significant role in semiconductor electronics. To enhance the electrical properties of these films, one approach is thickness increment which degrades the optical properties. However, a preferred way to optimize both electrical and optical properties of these layers is to introduce a buffer layer. In this work, the effects of buffer layer and film thickness on the structural, electrical, optical and morphological properties of AZO thin films are investigated. Al-doped zinc oxide (AZO) is prepared at various thicknesses of 100 to 300 nm on the bare and 100 nm-thick indium tin oxide (ITO) coated glass substrates by radio frequency sputtering. Results demonstrate that by introducing ITO as a buffer layer, the average values of sheet resistance and strain within the film are decreased (about 76 and 3.3 times lower than films deposited on bare glasses), respectively. Furthermore, the average transmittance of ITO/AZO bilayer is improved nearly 10% regarding single AZO thin film. This indicates that bilayer thin films show better physical properties rather than conventional monolayer thin films. As the AZO film thickness increases, the interplanar spacing, d₍₀₀₂₎, strain within the film and compressive stress of the film in the hexagonal lattice, decreases indicating the higher yield of AZO crystal. Moreover, with the growth in film thickness, carrier concentration and optical band gap (E_g) of AZO film are increased from 4.62?×?10¹⁹ to 8.21?×?10¹⁹ cm^?3 and from 3.55 to 3.62 eV, respectively due to the Burstein-Moss (BM) effect. The refractive index of AZO thin film is obtained in the range of 2.24–2.26. With the presence of ITO buffer layer, the AZO thin film exhibits a resistivity as low as 6?×?10^?4 Ω cm, a sheet resistance of 15 Ω/sq and a high figure of merit (FOM) of 1.19?×?10⁴ (Ω cm)^?1 at a film thickness of 300 nm. As a result, the quality of AZO thin films deposited on ITO buffer layer is found to be superior regarding those grown on a bare glass substrate. This study has been performed over these two substrates because of their significant usage in the organic light emitting diodes and photovoltaic applications as an enhanced carrier injecting electrodes.     

Depth dependent properties of ITO thin films grown by pulsed DC sputtering

A systematically prepared set of ITO layers for solar cell applications has been analyzed by spectroscopic variable angle ellipsometry in order to trace the dependence of free carriers’ distribution along the film depth as a function of film thickness as well as its change upon annealing. Samples were deposited on silicon substrates with various thicknesses in steps of approximately 10–20 nm. This set was duplicated and these samples were annealed, so that for each thickness an as-deposited and an annealed sample is available. Conventionally measured electrical conductivity and morphological properties (AFM measurements) of the films have been compared with the optical constants’ inhomogeneity, i.e. material properties along the film thickness modelled by variable-angle spectroscopic ellipsometry. The obtained results show that the optical as well as electrical properties of thin ITO films prepared by pulsed DC sputtering are depth dependent. For the deposition conditions used a well-determined reproducible non-uniform distribution of free carriers within the film thickness was determined. In particular it has been found that the majority of free carriers in as-deposited ultra-thin ITO films is concentrated at sample half-depth, while their distribution becomes asymmetric for the thicker films, with a maximum located at approximately 40 nm depth. The distribution of free carriers in annealed samples is qualitatively different from that of as-deposited layers.     

ITO及WO3在电解液中的交流阻抗特性

采用表面过程法拉第阻纳表达式方法与等效电路方法，研究透明ITO平面电极及带WO3薄膜层的ITO平面电极处于1mol LiClO4丙烯碳酸酯电解液中的电化学阻抗谱．分析显示WO3薄膜层有效地阻止了表面吸附参量对ITO电极反应的影响，使电极反应仅受电极电位的影响，并且随WO3薄膜在电解液中浸泡时间的增加，WO3薄膜的常相位角元件的特性最终回归为电容效应．     

Preparation of transparent conductive indium tin oxide thin films from nanocrystalline indium tin hydroxide by dip-coating method

Indium tin oxide (ITO) thin films with well-controlled layer thickness were produced by dip-coating method. The ITO was synthesized by a sol-gel technique involving the use of aqueous InCl₃, SnCl₄ and NH₃ solutions. To obtain stable sols for thin film preparation, as-prepared Sn-doped indium hydroxide was dialyzed, aged, and dispersed in ethanol. Polyvinylpyrrolidone (PVP) was applied to enhance the stability of the resulting ethanolic sols. The transparent, conductive ITO films on glass substrates were characterized by X-ray diffraction, scanning electron microscopy and UV-Vis spectroscopy. The ITO layer thickness increased linearly during the dipping cycles, which permits excellent controllability of the film thickness in the range ~ 40-1160 nm. After calcination at 550 °C, the initial indium tin hydroxide films were transformed completely to nanocrystalline ITO with cubic and rhombohedral structure. The effects of PVP on the optical, morphological and electrical properties of ITO are discussed.     

直流磁控溅射功率对ITO薄膜光学性能的影响

本实验的ITO薄膜样品是利用直流磁控溅射技术在玻璃基片上沉积而成的。通过改变溅射功率,研究不同溅射功率对ITO薄膜光学性能的影响。经各实验测试后发现：在实验给定的功率区间内,ITO薄膜的厚度随着溅射功率的增加而增加,其可见光透过率则随之降低。     

石英基片上(110)取向PLZT薄膜及其光学性能研究

在低成本的石英玻璃衬底上制备高性能电光薄膜非常有吸引力。本文采用溅射方法,并结合Pb3O4气氛退火工艺,在ITO/石英玻璃衬底上制备锆钛酸铅镧(PLZT 8/65/35)薄膜。结果表明:在优化工艺条件下,薄膜为(110)方向择优生长,表面均方根粗糙度为3.1nm,可见光范围内透过率为81.3%,消光系数为0.003。这种表面光滑和高光学性能的PLZT薄膜在集成光学和光电子器件具有重要的应用潜力。     

Spectrographic ellipsometry study of a liquid crystal display substrate consisting of thin films of SiO2, polyimide and indium tin oxide on glass

Variable angle spectrometric ellipsometry at room temperature is used to determine thin film parameters of substrates used in liquid crystal displays. These substrates consist of sequential thin films of polyimide (PI), on indium tin oxide (ITO),on SiO₂ deposited on a glass backing approximately 1.1 mm thick. These films were studied by sequentially examining more complex systems of films (SiO₂, SiO₂-ITO, SiO₂-ITO-PI). The SiO₂ layer appears to be optically uniform and flat. The ITO film is difficult to characterize. When this surface film's lower surface is SiO₂ and upper surface is an air-ITO-interface it is found that including surface roughness and variation of the optical properties with ITO thickness in the model improved the fit; suggesting that both phenomena exist in the ITO films. However, the surface roughness and graded nature of optical properties could be not determinable by ellipsometry when the ITO is coated with a polyimide film. The PI films are ellipsometrically flat and over the wavelength range from 500 to 1400 nm the real refractive index of polyimide films varying in thickness between 25 and 80 nm is well modeled by a two-term Cauchy model with no absorption. The ellipsometric thickness of the ITO layer is the same as the profilometric thickness; however, the ellipsometric thickness of the polyimide layers is roughly 10 nm larger than that obtained from the profilometer. These final observations are consistent with the literature.     

Preparation of regularly structured nanotubular TiO2 thin films on ITO and their modification with thin ALD-grown layers

Nanotubular titanium dioxide thin films were prepared by anodization of titanium metal films evaporated on indium tin oxide (ITO) coated glass. A facile method to enhance the adhesion of the titanium film to the ITO glass was developed. An optimum thickness of 550 nm for the evaporated titanium was found to keep the film adhered to ITO during the anodization. The films were further modified by growing amorphous titania, alumina and tantala thin films conformally in the nanotubes by atomic layer deposition (ALD). The optical, electrical and physical properties of the different structures were compared. It was shown that even 5 nm thin layers can modify the properties of the nanotubular titanium dioxide films.     

Effect of sputtering power and annealing temperature on the properties of indium tin oxide thin films prepared from radio frequency sputtering using powder target

Indium tin oxide (ITO) thin films were deposited on quartz substrates by radio frequency (RF) sputtering with different RF power (100–250 W) using the powder target at room temperature. The effect of sputtering power on their structural, electrical and optical properties was systematically investigated. The intensity of (400) orientation clearly increases with the sputtering power increases, although the films have (222) preferred orientation. Increasing sputtering power is benefit for lower resistivity and transmittance. The films were annealed at different temperature (500–800 °C), then we explored the relationship between their electro-optical and structural properties and temperature. It has been observed that the annealed films tend to have (400) orientation and then show the lower resistivity and transmittance. The ITO thin film prepared by RF sputtering using powder target at 700 °C annealing temperature and 200 W sputtering power has the resistivity of 2.08 × 10^?4 Ω cm and the transmittance of 83.2 %, which specializes for the transparent conductive layers.     

RF sputtered ZnO-ITO films for high temperature CO sensors

In this work is reported the development of ceramic sensors based on ZnO-doped ITO thin films for engine diagnostics able to withstand the harsh environments associated with exhausts. ZnO-ITO films were deposited by RF-sputtering and have been employed in the development of thin films-based carbon monoxide resistive sensors operating at high temperature (500 °C). ZnO-ITO films, with different Zn/In ratio and thickness around 3 µm., have been deposited by changing the power on the targets. The effects of both the working temperature and the ZnO loading on the sensors performances were investigated. Undoped ITO film has shown negligible response to CO, whereas ZnO-ITO films were found to be sensitive at the required working temperatures. The reported results show how the ZnO-ITO devices under study can be promising sensors for CO monitoring in real exhausts of car engines.     

Stability of nano-thick transparent conducting oxide films for use in a moist environment

The stability of nano-thick transparent conducting oxide thin films in a high humidity environment was investigated. The stability of ITO and impurity-doped ZnO thin films prepared with a thickness in the range from approximately 20 to 100 nm on glass substrates at a temperature below 200 °C by a pulsed laser deposition was evaluated in air at a relative humidity of 90% and a temperature of 60 °C. The resistivity of all Al- and Ga-doped ZnO thin films tested was found to increase markedly with test time, whereas that of ITO remained relatively stable; the stability (resistivity increase) of the doped ZnO thin films was considerably affected by film thickness but was relatively independent of the deposition substrate temperature. In particular, doped ZnO thin films with a thickness below approximately 50 nm were very unstable under the test conditions. The resistivity increase of doped ZnO films is mainly attributed to the grain boundary scattering resulting from the adsorption of oxygen on the grain boundary.     

ZnO:Al thin films deposited by RF-magnetron sputtering with tunable and uniform properties

Nanostructured, high quality and large area Al-doped ZnO (ZnO:Al) thin films were obtained by radiofrequency (RF) magnetron sputtering. The sample rotation during deposition has resulted in excellent spatial distribution of thickness and electro-optical properties compared to that obtained under static conditions. ZnO:Al thin films are employed in a large number of devices, including thin film solar cells, where the uniformity of the properties is a key factor for a possible up-scaling of the research results to industrially relevant substrate sizes. A chemical post etching treatment was employed achieving tunable surface nanotextures to generate light scattering at the desired wavelength for improved cell efficiency. Since the film resistivity is only slightly increased by the etching, this post-deposition step allows separating the optimization of electro-optical properties from light scattering behavior. The thin films were characterized by FE-SEM, XRD, UV-VIS spectroscopy, four probe and van der Paw techniques.