Study on the electrical and optical properties of ITO and AZO thin film by oxygen gas flow rate

Transparent conductive oxide (TCO) thin films such as tin doped indium oxide (ITO), zinc doped indium oxide (IZO) and Al doped zinc oxide (AZO) have been widely used as transparent electrode for display. ITO and AZO thin films for display was prepared by the facing targets sputtering (FTS) system. The FTS method is called a plasma-free sputter method because the substrate is located apart from plasma. This system can deposit the thin film with low bombardment by high energetic particles in plasma such as γ-electrons, negative ions and reflected Ar atoms. ITO and AZO thin films were deposited on glass substrate at room temperature with oxygen gas flow rate and input power. And the electrical, structural and optical properties of the thin films were investigated. As a result, the resistivity of ITO, AZO thin film is 6?×?10^?4 Ω cm, 1?×?10^?3 Ω cm, respectively. And the optical transmittance of as-deposited thin films is over 80% at visible range.     

PEMFC不锈钢双极板离子镀CrNX薄膜表面改性

用电弧离子镀膜技术通过改变N2流量的方法,在质子交换膜燃料电池(PEMFC)中用不锈钢双极板表面沉积一系列不同N含量的CrNx改性薄膜,对薄膜的成分、结构与接触电阻、耐蚀性能进行了测试。结果表明,沉积CrNx薄膜能够明显改善双极板的表面性能,并且其性能随着薄膜中N含量的变化而变化。与原始不锈钢相比,接触电阻降低1个数量级,耐腐蚀性能提高2个数量级。其中N含量为46.2%时,接触电阻降低到了11.8mΩ·cm(20.8MPa夹紧力);N含量为50.5%时,极化电流降低到10-7A/cm(2电极电位为0.6V)。分析表明,双极板处理后性能的改善与电弧离子镀薄膜的致密度较高,以及薄膜的成分、结构随薄膜中N含量的变化有关。     

Characterization of PT ferroelectric thin films on porous silica for pyroelectric IR detectors

Ferroelectric PbTiO₃ thin films were deposited on Pt/DS/PS/SiO₂/Si substrates by sol–gel technique. Porous silica (PS) thin film was used as thermal-insulation layer and dense silica (DS) thin film was a buffer layer to reduce surface roughness of PS layer. Root mean square surface roughness can be effectively reduced from 9.7 to 3.5 nm after PS buffer layer was prepared. The average grain size of PT thin films decreased slightly with increasing thickness of porous silica. Dielectric constant of PT increased from 107 to 171 at 1 KHz as thickness of PS layer increased from 0 to 2,000 nm. PT thin film prepared on 2,000 nm porous silica exhibited good dielectric property. The leakage current density was less than 1.6?×?10^-6 A/cm² when the applied electrical field was 200 kV/cm. The composite film is suitable for preparing pyroelectric IR detectors.     

不锈钢双极板表面电弧离子镀Cr/CrN/Cr薄膜研究

用电弧离子镀方法,在质子交换膜燃料电池用不锈钢双极板试样表面沉积三明治结构的Cr/CrN/Cr多层薄膜,对双极板与碳纸的接触电阻和在模拟腐蚀液中的电化学腐蚀性能等进行了测试.结果表明,镀膜处理使不锈钢表面性能有明显改善,与原始不锈钢相比,其接触电阻降低了一个数量级;同时,电化学耐腐蚀性能也得到显著提高.分析表明,这与薄膜表面平整、致密且膜基结合力强,以及薄膜的Cr/CrN/Cr多层结构的复合作用有关.     

Effects of sputtering pressure and thickness on properties of ZnO:Al films deposited on polymer substrates

Highly conducting and transparent aluminum doped zinc oxide (ZnO:Al) thin films have been deposited on polyimide substrate by r.f. magnetron sputtering at room temperature. The influence of sputter pressure and thickness on the structural, electrical, and optical properties of ZnO:Al films deposited on polyimide substrate is reported. The crystallinity and degree of orientation was increased by decreasing the sputter pressure. For higher sputtering pressures an increase on the resistivity was observed due to a decrease on the mobility and the carrier concentration. As the film thickness was increased, the crystallite sizes were increased, but the average transmittance in the wavelength range of the visible spectrum was decreased. The electrical performances of the ZnO:Al films deposited on glass substrates are slightly worse than the ones of the films deposited on polyimide substrates with same thickness. The lowest resistivity of 8.6?×?10^?4 Ω cm can be obtained for films deposited on glass substrate with the thickness of 800 nm.     

Effects of substrate temperature on electrical and optical properties ITO films deposited by r.f. magnetron sputtering

Indium tin oxide (ITO) films have been prepared by r.f. magnetron sputtering using powder target. X-ray diffraction analysis indicates that the deposited films were polycrystalline and retained a cubic bixbite structure. The ITO films deposited at low substrate temperature (T _s) exhibit a (411) preferred orientation but the films deposited at high T _s prefer a (111) orientation. The substrate temperature was found to significantly affect the electrical properties. As the T _s was increased, the conductivity of ITO films was improved due to thermally induced crystallization. The lowest resistivity (8.7?×?10^?4 Ω-cm) was obtained from ITO films deposited at 450 °C. However, optical properties of the films were somewhat deteriorated. The infrared (IR) reflectance of the film increases with increasing the substrate temperature.     

Fabrication and characterization of Au/SBT/LZO/Si MFIS structure

Ferroelectric SrBi₂Ta₂O₉ (SBT) films on a p-type Si (100) wafer with a LaZrO _x (LZO) buffer layer have been fabricated to form a metal-ferroelectric-insulator–semiconductor (MFIS) structure. The LZO thin film and SBT films were deposited by using a sol–gel method. The equivalent oxide thickness (EOT) value of the LZO thin film was about 8.83 nm. Also, the leakage current density of the LZO thin film is about 3.3?×?10^?5 A/cm² at bias sweeping voltage of ±5 V. SBT films were crystallized in polycrystalline phase with highly preferred (115) orientation. Also, the intensity of each pick slightly increased as thickness of SBT films increased. The C–V characteristics of Au/SBT/LZO/Si structure showed clockwise hysteresis loop. The memory window width increased as the thickness of SBT films increased. The leakage current density of Au/SBT/LZO/Si structure decreased as thickness of SBT films increased.     

Low-temperature synthesis of barium titanate thin films by nanoparticles electrophoretic deposition

The nanoparticles electrophoretic deposition (EPD) of barium titanate (BaTiO₃ or BTO) thin films was investigated. BTO nanocrystallites in a pseudocubic perovskite phase with an average particle size of about 10 nm were synthesized at a low temperature of 90°C by a high-concentration sol–gel process. By using a mixed solvent of 2-methoxyethanol and acetylacetone as dispersing medium, transparent and well-dispersed BTO nanocrystallites suspensions within the concentration range of 0.0125 to 0.20 mol/l was successfully prepared for nanoparticles EPD. A uniform microstructure and a smooth surface were observed on the deposited films. The film thickness of the deposited films increased rapidly with increasing EPD time in the initial period of EPD, and thereafter gradually increased to a limited thickness. With increasing applied EPD voltage, the limited film thickness increased. A near linear relation between the film thickness of films and the concentration of suspensions was observed under the same EPD conditions. The microstructures of the deposited BTO thin films were investigated.     

Growth characteristics and film properties of gallium doped zinc oxide prepared by atomic layer deposition

We carried out comprehensive studies on structural, optical, and electrical properties of gallium-doped zinc oxide (Ga:ZnO) films deposited by atomic layer deposition (ALD). The gallium(III) isopropoxide (GTIP) was used as a Ga precursor, which showed pure Ga₂O₃ thin film with high growth rate. Using this precursor, conductive Ga doped ZnO thin film can be successfully deposited. The electrical, structural and optical properties were systematically investigated as functions of the Ga doping contents and deposition temperature. The best carrier concentration and transmittance (7.2?×?10²⁰ cm^?3 and 83.5 %) with low resistivity (≈3.5?×?10^?3?Ωcm) were observed at 5 at.% Ga doping concentration deposited at 250 °C. Also, low correlation of deposition temperature with the carrier concentration and film structure was observed. This can be explained by the almost same atomic radius of Ga and Zn atom.     

Effect of Deposition Temperature on the Electrochromic Properties of Electron Beam-Evaporated WO3 Thin Films

Tungsten oxide (WO₃) thin films were deposited on ITO/glass substrates using the electron beam evaporation technique. The WO₃ films were grown on substrates at temperatures varying from room temperature (RT) to 240 °C. The structural characterization and surface morphology were examined using X-ray diffraction (XRD) and a field emission scanning electron microscope (FE-SEM). The electrochromic properties of WO₃ thin films were investigated using cyclic voltammograms (CVs) and in situ transmittance measurements, which were performed on WO₃ thin films immersed in an electrolyte of 1 M LiClO₄ in propylene carbonate (PC). An amorphous 510-nm-thick WO₃ film heated at RT exhibits the maximum transmittance variation (ΔT%) of 61.8% between the bleached state and the colored state, with a ΔOD of 0.739, Q of 17.31 mC/cm² and η of 42.69 cm²/C at a wavelength (λ) of 550 nm.     

Electrical, optical, and structural properties of ITO co-sputtered IZO films by dual target magnetron sputtering

We have investigated electrical, optical, and structural properties of indium tin oxide (ITO) co-sputtered indium zinc oxide (IZO) film prepared by a dual target direct current (DC) magnetron sputtering at room temperature in pure Ar ambient. It was shown that the resistivity and sheet resistance of ITO co-sputtered IZO films monotonically increased with increasing DC power of ITO target at constant DC power of IZO target. Synchrotron X-ray scattering and scanning electron microscope examination results show that addition of ITO in the IZO film lead to crystallization of IZTO film due to low transition temperature of the ITO from amorphous to crystalline. However, ITO co-sputtered IZO film (ITO/IZO power?=?100 W:100 W) exhibit higher work function than those of pure IZO and ITO film. It was found that the work function as well as the electrical, optical, and surface properties of the IZTO film could be controlled by varying the DC power of IZO and ITO targets, respectively.     

Preparation of thick PZT films on stainless steel substrates

Abstract

Lead zirconate titanate (PZT, PbZr_0.52Ti_0.48O₃) films of thickness 22 μm have been deposited on stainless steel substrates by spin-coating a PZT solution containing PZT powder. The solution had a concentration of 1.2 M and was dispersed with PZT powder in a 1:1 powder/solution molar ratio. The films were rapidly heated to 400°C and annealed for 15 min, and then they were further annealed in an oven at 650°C for 30 min. The results of X-ray diffraction studies show that the films have a pure perovskite phase. The inter-diffusion of ions at the PZT/stainless steel interface was prevented by using a ZrO₂ barrier layer. The films were found to have good ferroelectric and piezoelectric properties.     

ZAO特性及其在CIGS电池中的应用

透明导电氧化物薄膜(Transparent Conductive Oxides,简称TCO)用途广泛,介绍了TCO应用于光伏领域中的铜铟镓硒薄膜(CIGS)太阳电池,是CIGS太阳电池中不可缺少的一部分。简要阐述了其可见光范围内的透明性和导电性及其成因,以及作为CIGS薄膜太阳电池中窗口层的作用。将ITO和ZAO透明导电薄膜在CIGS太阳电池的应用进行相比,以掺铝的氧化锌(ZnO∶Al简称ZAO)透明导电薄膜为例,对其性能、制备方法及过程进行了简要阐述,并概括了大面积ZAO薄膜的性能。     

靶材密度对射频磁控溅射法制备ITO薄膜性能的影响

以不同密度的氧化锡铟（ITO））靶材为原料,采用射频磁控溅射法,在室温下沉积并经750℃退火,获得了电阻率为1．56×10^-4Ω·cm、可见光透过率为87％的ITO薄膜。对不同密度靶材制备的ITO薄膜的微观结构、电学及光学性能进行了表征与探讨。结果表明,采用射频磁控溅射法时,不同靶材密度对ITO薄膜的沉积速率、结构、电学和光学性能均无显著影响。该结果为采用低密度ITO靶材制备高品质ITO薄膜提供了一个新的思路。     

Application of HfO2 high-k gate insulator for excimer laser annealed poly-Si TFT

The electrical characteristics of polycrystalline silicon (poly-Si) thin film transistor (TFT) crystallized by excimer laser annealing (ELA) method with high-k gate dielectrics were evaluated. Because a high thermal budget is inevitable for conventional fabricating process of poly-Si TFTs, an amorphous silicon film on a buried oxide was crystallized by annealing with a KrF excimer laser (248) to fabricate a poly-Si film at low temperature. Furthermore, the high permittivity HfO₂ film with a thickness of 20 nm as the gate-insulator was deposited by atomic layer deposition (ALD) to low temperature process. In addition, the solid phase crystallization (SPC) was compared to the ELA method as a crystallization technique of amorphous-silicon film. As a result, the crystallinity and surface roughness of poly-Si crystallized by ELA method was superior to the SPC method. Also, we obtained excellent device characteristics from the poly-Si TFT fabricated by the ELA crystallization method.     

A study of phase transformations in rapid thermal processed sol gel PZT using glancing angle x-ray diffraction

Abstract

A technique is established for depth profiling of thin film PZT using glancing angle x-ray diffraction. The transformation of PZT from the pyrochlore to perovskite phase is monitored throughout the thickness of the films. Thin film PZT was deposited using the sol gel technique. The effects of substrate, linear ramp rate, hold temperature and hold time on crystal nucleation and growth were investigated using rapid thermal annealing. The films crystallized on platinum into the perovskite phase through a highly textured interfacial region to a non-textured region at the surface, while films on ITO showed a random texture. Transforming the PZT films to perovskite and limiting the texture to the interfacial region was achieved using a ramp rate of 50°C/s and a hold time of 650°C/30s.     

Effect of seed layers on dielectric properties of Ba(Zr0.3Ti0.7)O3 thin films

The Barium zirconium titanate Ba(Zr_0.3Ti_0.7)O₃ thin films were prepared on Pt/Ti/SiO₂/Si substrates with seed layers at the BZT/Pt interface by sol–gel process. Microstructure and structure of thin films were examined. Dielectric properties of thin films with various seed layers thicknesses were investigated as a function of frequency and direct current electric field. The tunability and dielectric constant of BZT thin films increased with increasing seed layer thickness from 0 to 20 nm, while it decreased with a further increase in thickness above 20 nm, meanwhile, the leakage current showed the similar tendency at applied electric field of 250 kV/cm. The optimized seed layer thickness for BZT thin films plays an important role in maintaining the high tunability and low leakage current, which are suitable for microwave device applications.     

Electrodes for ferroelectric thin films

Abstract

Platinum and ruthenium oxide (RuO₂) deposited by ion beam sputter-deposition are evaluated for use as electrodes for PZT thin film capacitors. The effect of deposition temperature, film thickness, and the presence of oxygen on hillock formation in platinum is discussed. It is shown that the hillock density in Pt/Ti/SiO₂/Si films can be significantly reduced by properly controlling the processing conditions and film thickness. Stress measurements correlate with the experimental observation that depositing thinner platinum films (<800 Å) is an effective means of reducing hillock formation. The use of an intermediate deposition temperature 200–250°C also helps minimize hillock formation. Diffusion of the Ti adhesion layer into and/or through the platinum was significantly reduced by replacing the Ti with a TiO_x adhesion layer. RuO₂ electrodes are compared to Pt in terms of resistivity, surface morphology, microstructure and film orientation.     

Electrical and optical properties of fluorine-doped tin oxide (SnOx:F) thin films deposited on PET by using ECR–MOCVD

The electrical, optical, structural and chemical bonding properties of fluorine-doped tin oxide (SnO_x:F) films deposited on a plastic substrate prepared by Electron Cyclotron Resonance–Metal Organic Chemical Vapor Deposition (ECR–MOCVD) were investigated with special attention to the process parameters such as the H₂/TMT mole ratio, deposition time and amount of fluorine-doping. The four point probe method, UV visible spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic emission spectroscopy (AES), X-Ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were employed to characterize the films. Based on our experimental results, the characteristics of the SnO_x:F thin films were significantly affected by the process parameters mentioned above. The amount of fluorine doping was found to be one of the major parameters affecting the surface resistivity, however its excess doping into SnO₂ lead to a sharp increase in the surface resistivity. The average transmittance decreased with increasing film thickness. The lowest electrical resistivity of 5.0?×?10^?3 Ω^.cm and highest optical transmittance of 90% in the visible wavelength range from 380 to700 nm were observed at an H₂/TMT mole ratio of 1.25, fluorine-doping amount of 1.3 wt.%, and deposition time of 30 min. From the XRD analysis, we found that the SnO_x:F films were oriented along the (2 1 1) plane with a tetragonal and polycrystalline structure having the lattice constants, a?=?0.4749 and c?=?0.3198 nm.     

MOCVD of (Ba,Sr)TiO3: Nucleation and Growth

(Ba_0.7Sr_0.3)TiO₃ and SrTiO₃ thin films were deposited on Pt electrodes in a planetary multi-wafer MOCVD reactor. The nucleation behavior and the size of the stable nuclei were investigated by different SPM techniques. Characteristic differences were observed for different deposition temperatures, i.e. a homogeneous nucleation of small BST grains on the larger Pt grains at 565°C and a dominating nucleation at the grain boundaries at 655°C. The micro structural evolution after further film growth was investigated by HRTEM and revealed randomly oriented grains (typical inplane size 10–20 nm) with a high density of twins at 565°C and (100)-oriented defect free grains of only slightly increased size at 655°C. For SrTiO₃ the inplane grain size was increased, however, the (100) texture was less perfect. As the electrical properties like permittivity and also leakage current depend on film thickness the final discussions of the electrical properties are based on thickness series (5 nm–100 nm films) and evaluated within the phenomenological dead layer model.