Potentiostatic electrodeposition of cuprous oxide thin films for photovoltaic applications

Potentiostatic deposition of Cu₂O thin films on glass substrates coated with F-doped SnO₂ from an alkaline electrolyte solution (pH 12.5) containing copper (II) sulfate and lactic acid was studied for fabrication of a Cu₂O/Al-doped ZnO (AZO) heterojunction solar cell. The band gap of the electrodeposited Cu₂O films was determined by photoelectrochemical measurements to be around 1.9 eV irrespective of the applied potentials. The solar cells with a glass/FTO/Cu₂O/AZO structure were fabricated by sputtering an AZO film onto the Cu₂O film followed by deposition of an Al contact by vacuum evaporation. The highest efficiency of 0.603% was obtained with a Cu₂O film deposited at −0.6 V (vs. Ag/AgCl). This was attributed to better compactness and purity of the Cu₂O film than those of the Cu₂O films deposited at other potentials.     

不同衬底上ZnO:Al透明导电薄膜的性能

室温下,采用射频磁控溅射法在玻璃和聚对苯二甲酸乙二醇酯（polyethylene terephthalate,PET）上沉积了掺铝的氧化锌（ZnO：Al,AZO）透明导电薄膜。通过X射线衍射仪分析不同衬底上AZO薄膜的结构,采用四探针测试仪及紫外可见光分光光度计测试薄膜的光电性能。结果表明：沉积在两种衬底上的AZO薄膜都具有六方纤锌矿结构,最佳取向均为[002]方向;玻璃衬底和PET衬底上制备的AZO薄膜的方阻分别为19/sq和45/sq,薄膜透光率均高于90%。实验表明,柔性衬底透明导电氧化物薄膜可以代替硬质衬底透明导电薄膜使电子器件向小型化、轻便化方向发展。     

Comparative studies of polypropylene nonwoven sputtered with ITO and AZO

In this study, the polypropylene (PP) spunbonded nonwoven materials were used as substrates for depositing transparent nanostructures on the fiber surfaces. Magnetron sputter coating technique was used to deposit tin‐doped indium oxide (ITO) and aluminum‐doped zinc oxide (AZO) films onto the nonwoven substrates. The structures and properties of the deposited ITO and AZO films were investigated and compared using atomic force microscopy, energy‐dispersive X‐ray (EDX), and electrical and optical tests. The observations by atomic force microscopy revealed the formation of functional nanostructures on the fiber surfaces. EDX analyses confirmed the deposition of ITO and AZO functional films on the PP fibers. It was found that ITO had more compact structures on the fiber surface than AZO under the same sputtering conditions. The transmittance analysis revealed that the nonwoven substrates deposited with nanostructural AZO showed better ultraviolet shielding effect than those coated with ITO in the same thickness. The nonwoven materials coated with ITO had lower electrical resistance than those coated with AZO in the same thickness. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Chemical solution deposition of pure and Gd-doped ceria thin films: Structural,morphological and optical properties

High quality smooth, uniform and crack-free ceria and gadolinium doped ceria (GDC) thin films were prepared on Si and Si/YSZ substrates by chemical solution deposition. The thermal behavior of Gd-Ce-O precursor was investigated by TG-DSC measurements. The phase purity and structure of deposited films were evaluated using X-ray diffraction (XRD) analysis and Raman spectroscopy. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were employed for the estimation of surface morphological features. Oxidation state of Ce ions in fabricated films was analyzed by X-ray photoelectron spectroscopy (XPS). Optical properties were evaluated by diffuse reflectance UV–vis spectrometry. Thickness of the films can be controlled by applying a certain number of spin coating cycles. A linear relation between the thickness of the films and the number of deposited layers was observed. The single-layer thickness was determined to be approximately 20 nm. The influence of annealing temperature and Gd content on the film structure, morphology and optical properties was studied and discussed. The dependence of an optical band gap as a function of grain size was demonstrated.     

在ITO玻璃衬底上制备锆钛酸铅铁电薄膜

利用射频反应性溅射沉积技术在掺的Ｓｎ的Ｉｎ２Ｏ３导电透明膜衬底上制备了钙钛矿型Ｐｂ（Ｚｒ,Ｔｉ）Ｏ３（ＰＺＴ）铁电薄膜。研究了沉积参量与热处理工艺对铁电薄膜结构和性能的影响。运用Ｘ射线衍射、Ｘ射线光电子能谱和扫描电镜等技术,分析了薄膜的晶体结构、表面形貌和表面元素化学状态。测量了不同处理条件下薄膜的铁电性能。结果表明：在掺Ｓｎ的Ｉｎ２Ｏ３导电透明膜衬底上可以得到表面无裂纹,化学计量比符合要求的ＰＺ     

Yttria-stabilized zirconia thin films with restrained columnar grains for oxygen ion conducting electrolytes

Yttria-stabilized zirconia thin films with restrained columnar grains were deposited by modifying the DC reactive magnetron sputtering conditions. Usually, films fabricated by physical vapor deposition (PVD) method generate columnar grain structures due to its deposition characteristics. The grain boundaries between these columnar grains can be considered as structural defects and causes serious issues for the application of thin film electrolyte of energy conversion systems. By modifying the background pressure and deposition temperature of the reactive sputtering method, YSZ thin films having restrained columnar grains were successfully fabricated. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations were conducted to analyze the surface morphologies, grain structures, and nano-defects in the interior of the YSZ thin film. Through the analysis, restrained columnar microstructures of the YSZ films were deposited as dense and homogeneous. The film also showed higher ionic conductivity compared to that of the columnar structure due to the reduced ion transport blocking effect. Moreover, the fuel cell fabricated with the YSZ electrolyte having restrained columnar grains showed superior performance in terms of the peak power density than the fuel cell with columnar grain electrolyte structure.     

Characterization of Pure and Al Doped ZnO Thin Films Prepared by Sol Gel Method for Solar Cell Applications

Pure and Al-doped Zin Oxide ZnO (AZO) thin films with different aluminum (Al) concentrations (0.5, 1, 2, and 3 at.%) were prepared on glass substrates by a dip-coating technique using different Zn and Al precursors. The structural, morphological, optical and electrical properties of these films were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), Atomic force electron microscopy, ultraviolet–visible spectrophotometry, photoluminescence (PL) spectroscopy and four-point probe technique. XRD results showed that the obtained AZO thin films were polycrystalline with a highly c-axis preferred (002) orientation, and the average crystallites size decreased from 29 to 25 nm with the increase in Al doping concentration. EDS microanalysis confirmed the presence of Zn, O and Al elements in the prepared films as expected. The optical study demonstrated that the ZnO thin film had a good transparency in the visible range with a maximum transmittance of 90% and the band gaps varied from 3.16 to 3.26 eV by Al doping. SEM micrographs showed a wrinkles-like morphology of the thin films that changed in density with the increase of Al concentrations. The PL emission spectra indicated that except the thin film doped with 1 at.%, other films exhibited high emission intensities under an excitation of 325 nm which allows to apply them as downconversion layers for solar cell applications.

     

制备过程对掺铝氧化锌薄膜性质的影响

文章采用溶胶-凝胶法在玻璃基底上制备得到了高透光率,高导电性的掺铝氧化锌薄膜（AZO）,利用原子力显微镜、扫描电镜、X射多次退火的制备过程不仅可以得到可见光区透光率大于85%,电阻率为7.2×10-5Ω·m的透明导电薄膜,而且因省略了热处理过程而简化了制备工艺,缩短了制膜时间。线衍射仪和紫外可见分光光度计等研究了三种不同的制备过程对AZO性质的影响。结果表明,制备过程的不同导致了薄膜的表面形貌、结构和导电性质方面的差别,其中分层多次退火过程有利于晶粒长大,形成结晶度高且具有单一（002）取向的AZO薄膜,同时改善薄膜的导电性能。分层     

Effects of NIR annealing on the characteristics of al-doped ZnO thin films prepared by RF sputtering

Aluminum-doped zinc oxide (AZO) thin films have been deposited on glass substrates by employing radio frequency (RF) sputtering method for transparent conducting oxide applications. For the RF sputtering process, a ZnO:Al₂O₃ (2 wt.%) target was employed. In this paper, the effects of near infrared ray (NIR) annealing technique on the structural, optical, and electrical properties of the AZO thin films have been researched. Experimental results showed that NIR annealing affected the microstructure, electrical resistance, and optical transmittance of the AZO thin films. X-ray diffraction analysis revealed that all films have a hexagonal wurtzite crystal structure with the preferentially c-axis oriented normal to the substrate surface. Optical transmittance spectra of the AZO thin films exhibited transmittance higher than about 80% within the visible wavelength region, and the optical direct bandgap (E_g) of the AZO films was increased with increasing the NIR energy efficiency.     

Preparation of Nanostructured ZnO Thin Films Using Magnetron Sputtering for the Gas Sensors Applications

ZnO is one of the most promising transparent conducting oxide materials, which widely used in thin film gas sensors. In this research, the dependence of the thermal oxidation time on structural, morphological and gas sensing properties of ZnO thin films is investigated. ZnO nanostructures are synthesized by using DC magnetron sputtering for deposition of pure zinc layers on glass substrates and then thermal oxidation of deposited zinc layers to produce zinc oxide (ZnO) thin films. Obtained results from X-ray diffraction revealed that the degree of crystallinity and the average grain size of the ZnO deposited thin films enhance with increasing the thermal oxidation time. Surface topography and growth behavior of ZnO thin films have important role in optimization of gas sensing properties of these films. In this study, scanning electron microscopy and atomic force microscopy have been used to investigate the effective parameters related to the surface topography of the films. Obtained results from these analyzes revealed that the surface topography of ZnO deposited samples strongly depend on thermal oxidation time. Also the effect of thermal oxidation time on the performance of ZnO gas sensors is investigated. The results indicated that the ethanol gas sensing properties of ZnO samples improve with decreasing the size of grains.     

Effect of annealing and room temperature sputtering power on optoelectronic properties of pure and Al-doped ZnO thin films

Transparent ZnO and Al-doped ZnO (AZO) thin films have been prepared by radio frequency sputtering deposition at room temperature. The optical, electrical, and structural characteristics of the obtained films have been extensively investigated as a function of sputtering and annealing parameters. Spectrophotometry, X-ray diffraction (XRD), atomic force microscopy (AFM), four-point probe and Hall-effect measurements were employed. The ZnO films generally exhibited excellent crystalline properties, while providing a UV cut-off in the absorption spectrum for optical filtration. AZO thin films exhibited an average transparency (larger than 85%) over the visible region of the spectrum, and resistivity of the order of 10^?3 Ω cm was obtained. The carrier concentration and electron mobility values proved to be dependent on the deposition parameters and annealing temperature. The obtained results showed that annealing temperatures higher than 400 °C were not necessary and potentially degraded the electronic properties of the AZO thin films.     

Influence of ZnO buffer layer on AZO film properties by radio frequency magnetron sputtering

Transparent conductive films of Al-doped zinc oxide (AZO) were deposited on glass substrates under various ZnO buffer layer deposition conditions (radio frequency (r.f.) power, sputtering pressure, thickness, and annealing) using r.f. magnetron sputtering at room temperature. This work investigates the influence of ZnO buffer layer on structural, electrical, and optical properties of AZO films. The use of grey-based Taguchi method to determine the ZnO buffer layer deposition processing parameters by considering multiple performance characteristics has been reported. Findings show that the ZnO buffer layer improves the optoelectronic performances of AZO films. The AZO films deposited on the 150-nm thick ZnO buffer layer exhibit a very smooth surface with excellent optical properties. Highly c-axis-orientated AZO/ZnO/glass films were grown. Under the optimized ZnO buffer layer deposition conditions, the AZO films show lowest electrical resistivity of 6.75 × 10⁻⁴ Ω cm, about 85% optical transmittance in the visible region, and the best surface roughness of R_a = 0.933 nm.     

Structural and Optical Characterization of Chemically Deposited PbS Thin Films

PbS thin films were deposited on glass substrates by a chemical bath deposition method. The effect of varying the film thickness on the structural and optical properties has been investigated. XRD analysis reveals the crystallinity of the deposited PbS films with (200) preferred crystal orientation. Increasing the film thickness enhances the crystallinity of the films as well as decreases the strain and dislocation density. The surface morphology features were dramatically changed from small spherical grains to bead-like shape. The absence of impurities in the deposited films was confirmed by energy dispersive x-ray spectrometry (EDX) measurements. The optical constants of the deposited films were calculated and a small decrease in the band gap energy was observed with increasing the film thickness.     

Physical properties of Al-doped ZnO films deposited on nonwoven substrates by radio frequence magnetron sputtering

In this study, the polyethylene terephthalate (PET) spunbonded nonwoven materials were used as substrates for creating electro-optical functional nanostructures on the fiber surfaces. A magnetron sputter coating was used to deposit Al-doped ZnO (AZO) films onto the nonwovens. The influences of the deposition time on the structural, optical, and electrical properties of AZO films were investigated. Atomic force microscopy (AFM) was employed to examine the topography of the fibers. The AFM observation revealed a significant difference in the morphology of the fibers before and after the AZO sputter coating. The examination by UV–visible spectrophotometer analysis showed that the nonwovens deposited with transparent nanostructure AZO films had better UV absorption, and an average transmittance was approximately 50% in the visible light wavelength region. The surface conductivity of the materials was analyzed using a four-probe meter, and it was found that electrical resistance was significantly decreased as the sputtering time increased.     

Nanoscale coaxial cables produced from vertically aligned carbon nanotube arrays grown via chemical vapor deposition and coated with indium tin oxide via ion assisted deposition

A highly conformal homogeneous indium tin oxide (ITO) thin film coating has been produced on vertically aligned carbon nanotube arrays by ion assisted deposition. The deposition process generates, in effect, a coaxial cable structure of ITO about a carbon nanotube. The deposited ITO films are uniformly 5 nm thick and have high crystallinity and excellent optical absorption properties, indicating they would be good candidates for use in solar cells, flexible electronics and displays. The materials are analyzed by scanning and transmission electron microscopy, X-ray diffraction, and visual light spectrometry.     

Fabrication of Pb(Zr,Ti)O3 thin films utilizing unconventional powder magnetron sputtering (PMS)

Pb(Zr,Ti)O3 (PZT) ferroelectric ceramic films exhibit highly superior ferroelectric, pyroelectric and piezoelectric properties which are promising for a number of applications including non-volatile random access memory devices, non-linear optics, motion and thermal sensors, tunable microwave systems and in energy harvesting (EH) use. In this research, a thin layer of PZT was deposited on two different substrates of Strontium Titanate (STO) and Strontium ruthenate (SRO) by powder magnetron sputtering (PMS) system. The preliminary powders, consisting of PbO, ZrO₂ and TiO_2, were manually mixed and placed into the target holder of the PMS. The deposition was performed at an elevated temperature reaching up to 600 °C via a ceramic heater. This high temperature is required for PZT thin film crystallinity, which is never achieved in conventional physical vapour deposition processes. The phase structure, crystallite size, stress-strain and surface morphology of deposited thin films were characterized using X-ray Diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM). The composition of the PZT thin films were also analysed by X-ray photoelectron spectroscopy (XPS). The mechanical properties of the thin films were evaluated with micro-scratch adhesive strength and micro hardness equipment. FESEM results showed that the PZT thin films were successfully deposited on both SRO and STO substrates. The surfaces of the coated samples were free from cracks, relatively smooth, uniform and dense. The profile of X-ray diffraction confirmed the formation of single-c-domain/single crystal perovskite phase grown on both substrates. The XPS analysis have shown that the PZT thin film grown by this method and that a target of PZT+10% PbO is a proper target for growing nominal PZT thin films. The adhesion strength and micro hardness results have confirmed the stability and durability of the thin film on the substrates, although higher values have been reported for thin film of PZT deposited on SRO surfaces.     

Effect of annealing temperature on structural and optoelectronic properties of γ-CuI thin films prepared by the thermal evaporation method

High quality transparent conducting CuI thin films were deposited at room temperature via thermal evaporation technique followed by post deposition annealing at different temperatures. The samples were characterised by X-ray diffraction (XRD), UV–Vis spectrophotometry, Scanning electron microscopy and I-V measurements. The structural, morphological and optical properties were studied as a function of the annealing temperature from room temperature (RT) to 200 °C. XRD results revealed that the films were polycrystalline with zinc blende structure of cubic phase. Increasing the annealing temperature increased the crystallite size from 33 to 49 nm whilst the dislocation density and lattice strain shifted to lower values. High transmittance of about 70–80% was exhibited by all films in the entire visible spectral range. The as deposited film possesed the lowest resistivity of 3.0×10⁻³ Ω cm.     

影响金刚石膜刀具涂层形貌的因素分析

采用高分辨金相显微镜对硬质合金刀生上沉各的ＣＶＤ金刚石薄膜进行了表面形貌和膜／基横截面组织形貌的观察;并利用该显微镜配备的功能测量了金刚石颗粒大小,膜厚;利用显微镜正焦／过焦观察判断了金刚石薄膜的成膜状况。初步观察结果表明：甲烷浓度和基体钴含量对金刚石薄膜的表面形貌和膜／基横截面组织形貌有显著的影响。     

Preparation and properties of AZO/PS/AZO tri-layer transparent conductive film with a light-trapping structure

The light-trapping structure is an effective method to increase solar light capture efficiency in the solar cells. In this study, Al-doped ZnO (AZO)/polystyrene (PS)/AZO tri-layer transparent conductive film with light-trapping structure was fabricated by magnetron sputtering and liquid phase methods. The structural, optical and electrical properties of the AZO films could be controlled by different growth conditions. When the sputtering pressure of the under-layer AZO film was 0.2 Pa, the discharge voltage was around 80 V, which was within the optimal process window for obtaining AZO film with high crystallinity. The optimal under-layer AZO film had a large surface roughness and a very low static water contact angle of 75.71°, promoting the relatively uniform distribution of PS spheres. Under this sputtering condition, the prepared AZO/PS/AZO tri-layer film had the highest crystallinity and least point defects. The highest carrier concentration and Hall mobility are 3.0 × 10²¹ cm^-3and 5.39 cm² V^-1 s^-1, respectively. Additionally, a transparent conductive film with the lowest resistivity value (3.88 × 10^-4 Ω cm) and the highest average haze value (26.5%) was obtained by optimizing the process parameters. These properties were comparable to or exceed the reported values of surface-textured SnO₂-based as well as ZnO-based TCOs films, making our films suitable for transparent electrode applications, especially in thin-film solar cells.     

Single step electrosynthesis of Cu2ZnSnS4 (CZTS) thin films for solar cell application

The Cu₂ZnSnS₄ (CZTS) thin films have been electrodeposited onto the Mo coated and ITO glass substrates, in potentiostatic mode at room temperature. The deposition mechanism of the CZTS thin film has been studied using electrochemical techniques like cyclic voltammetery. For the synthesis of these CZTS films, tri-sodium citrate and tartaric acid were used as complexing agents in precursor solution. The structural, morphological, compositional, and optical properties of the CZTS thin films have been studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), EDAX and optical absorption techniques respectively. These properties are found to be strongly dependent on the post-annealing treatment. The polycrystalline CZTS thin films with kieserite crystal structure have been obtained after annealing as-deposited thin films at 550 in Ar atmosphere for 1 h. The electrosynthesized CZTS film exhibits a quite smooth, uniform and dense topography. EDAX study reveals that the deposited thin films are nearly stoichiometric. The direct band gap energy for the CZTS thin films is found to be about 1.50 eV. The photoelectrochemical (PEC) characterization showed that the annealed CZTS thin films are photoactive.