Influence of the substrate type on the microstructural,optical and electrical properties of sol–gel ITO films

Indium tin oxide (ITO) is recognized as the best transparent and conductive material [transparent conducting oxide (TCO)] until now and its properties are dependent on the preparation method. In the present work ITO films with In:Sn atomic ratio 9:1 were prepared by a sol–gel route on different substrates (microscope glass slides, microscope glass covered with one layer of SiO₂ and Si wafers) for TCO applications. The multilayer ITO films were obtained by successive deposition by the dip-coating method and the films were characterized from the structural, morphological, optical, and electrical points of view using X-ray diffraction, scanning electron microscopy, atomic force microscopy, spectroscopic ellipsometry and by Hall effect measurements, respectively. The results showed that the thickness, optical constants and carrier numbers depend strongly on the type of substrate, number of deposited layers and sol concentration. The optical properties of ITO films are closely related to their electrical properties. The enhancement of the conductivity was possible with the increase of crystallite size (which occurred after thermal treatment) and with the reduction of surface roughness.     

Evolution of crystalline structure in SnS thin films prepared by chemical deposition

Crystal structure and morphology undergo significant evolution in thin films of tin(II) sulfide prepared by chemical deposition, over a narrow interval of bath temperature of 20–40 °C, but has not been recognized in previous studies. The chemical bath is constituted using tin(II) chloride, triethanolamine, ammonia(aq.) and thioacetamide. At bath temperature of 20 °C, the deposition rate of the film is 10 nm/h; and at 24 h, a film of thickness 260 nm is obtained. This film is compact and with a predominantly cubic (Cub-) crystalline structure. At 40 °C, the deposition rate is 25 nm/h, and a film of 600 nm in thickness is deposited in 24 h. However, this film has evolved into vertically stacked platelets of orthorhombic (OR-) crystalline structure. The transition from compact-to-platelet morphology as well as from Cub-to-OR-crystalline structure is observed near a deposition temperature, 35 °C. The Cub-SnS has a characteristic high optical band gap, 1.67 eV (direct gap; forbidden transitions) with an electrical conductivity, 10⁻⁷(Ω cm)⁻¹; both properties being un-affected when films are heated at 300 °C in a nitrogen ambient. In OR-SnS, the band gap is 1.1 eV (indirect gap; allowed transitions). The electrical conductivity of such films is notably higher, 10⁻⁴ (Ω cm)⁻¹, which increases further by an order of magnitude when the films have been heated at 300 °C in nitrogen.     

Synthesis and effect of post-deposition thermal annealing on morphological and optical properties of ZnO thin film

Zinc oxide thin films have been deposited on glass substrates by the chemical bath deposition method; a surfactant, cetyltrimethylammonium bromide (CTAB); was used as capping agent. The films were annealed at two different temperatures: 200 and 300 °C. The structural features were investigated by X-ray diffraction analysis which exhibited hexagonal wurtzite structures along with c-axis orientations. Crystallite size was estimated and found to be around 33–41 nm. The effect of post-deposition thermal annealing on the morphological and optical properties has been investigated by scanning electron microscopy and photoluminescence spectra at room temperature. The band gap energies of uncapped and CTAB-capped ZnO films were found to be 3.28 and 3.48 eV, respectively.     

Formation of CdS thin films in a chemical bath environment under the action of an external magnetic field

External magnetic fields were applied during thin film preparation of CdS on glass substrates by the chemical bath deposition technique (CBD). Some physical properties of the polycrystalline films, like layer thickness, grain size and optical quality depend in a characteristic manner on the strength and orientation of the external field during the growth process. The characterization of the samples includes atomic force microscopy (AFM), optical absorption, and dark conductivity measurements. The data interpretation follows a line based on the specific interaction of cadmium and sulfur ions with acting magnetic fields within the chemical bath This article was submitted by the authors in English.     

Sol–gel derived nanostructured nickel oxide films: Effect of solvent on crystallographic orientations

Nickel oxide films were deposited onto glass substrates by sol–gel dip coating method using solvents of different polarities without any catalysts, templates or surfactants. Methanol, 1,4-butanediol, ethanol, and 2-propanol were used as solvents. The structural, optical and electrical properties of NiO films were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–visible spectroscopy and Hall effect measurements, respectively. Nickel oxide thin films with cubic phase crystal structure of various preferred orientations were obtained in the different solvents. The XRD results showed that films deposited from solution using higher polar solvents develop a (1 1 1) preferred orientation, while the (2 0 0)-orientated films were obtained using lower polar solvents. The average particle size increases with viscosity of solvents. Surface morphology of the nickel oxide film consisted of nanoparticles with uniform coverage of the substrate surface. The solvent of higher viscosity induced larger particle size. Band gap narrowing from 4.42 to 3.87 eV was observed using different solvents. The lower resistivity and Hall coefficient was obtained for prepared NiO films using higher polar solvents. The relationships between solvent physicochemical properties, preferred orientation, structural, optical and electrical properties of NiO films were investigated.     

Structural,morphological and optical studies on chemically deposited nanocrystalline CdZnSe thin films

In the present paper, cadmium zinc selenide (Cd_0.5Zn_0.5Se) thin films were deposited on glass substrates by chemical bath deposition with optimized deposition parameters. 2-mercaptoethanol was used as a capping agent. The as-deposited thin films were annealed at 300, 500 and 700 °C and then subjected to various structural, morphological and optical investigations. The effect of the presence of capping agent and annealing on these properties was discussed. The phenomenon of phase transformation occurred during annealing. The optical band gap energies were found in the range 2.37–1.7 eV with respect to the annealing temperatures.     

Role of Organic Additives in the Sol-Gel Synthesis of Porous CaF2 Anti-Reflective Coatings

Porous CaF₂ anti-reflective coating films were prepared by the sol-gel method. Effects of organic additives on deposition and optical properties of the films were investigated. Amino alcohols (2-aminoethanol, 2-dimethylaminoethanol, and triethanolamine) and alcohols with larger molecular weights (ethyleneglycol, 2-methoxyethanol, cyclohexanol, and 2-(2-n-butoxyethoxy)ethanol) were chosen as the organic additives. Among these additives, cyclohexanol was the most effective to control the surface morphology and the optical properties of the films. By changing the amount of cyclohexanol in the coating solution, it was possible to control the optical thickness of the CaF₂ films. Accordingly, the wavelength giving the maximum transmittance could be changed in the UV region.     

Novel Electroless Deposition of Cu<Subscript>3</Subscript>Se<Subscript>2</Subscript> Film on Silicon Substrate by a Simple Galvanic Displacement Process

A novel electroless deposition method for depositing highly uniform adhesive thin films of copper selenide (Cu₃Se₂) on silicon substrates from aqueous solutions is described. The deposition is carried out by two coupled galvanic reactions in a single deposition bath containing copper cations, hydrogen fluoride, and selenous acid: the galvanic deposition of copper on silicon and the subsequent galvanic reaction between the deposited copper with selenous acid in the deposition bath. The powder X-ray diffraction and scanning electron microscopy are used to characterize and examine the deposited films.     

水浴法制备CdS薄膜产生的本征缺陷对光电学性质的影响

采用化学水浴沉积法(CBD)在钠钙玻璃衬底上制备硫化镉(CdS)薄膜,研究不同硫酸镉(CdSO_4)浓度下产生的本征缺陷对CdS薄膜光电学性质的影响。采用光致发光光谱、紫外-可见分光光度计及霍尔效应测试系统对薄膜的本征缺陷、光学及电学性质进行分析,发现CdS薄膜主要存在镉间隙(Cdi)及硫空位(VS)等本征缺陷,且VS随CdSO_4浓度的降低而逐渐减少。同时,VS缺陷的减少有利于薄膜透过率的提高,但在一定程度上降低了薄膜的电导率。根据透过率及其相关公式可知,半导体材料中透过率与电导率成e指数反比关系,适当减小薄膜的电导率可以使其透过率得到大幅度的提高,理论解释与实验结果相一致。     

沉积电位对电沉积ZnS薄膜的影响

采用电沉积方法,在不同沉积电位条件下,在氧化锡铟(ITO)导电玻璃上沉积制备了ZnS薄膜,利用XRD、SEM和UV-VIS测试技术对在不同沉积电位所制备薄膜的晶相结构、表面微观形貌和光学性能进行了表征.研究结果表明:沉积电位在1.5 V—1.7 V范围内制备的ZnS薄膜呈非晶态,其可见光透过率从60 %降低到20 %,薄膜的光学带隙约为3.97 eV.在沉积电位为2.0 V条件下所沉积薄膜为ZnS结晶相和金属Zn混合相,薄膜透过率显著降低.     

氮掺杂二氧化钛-氧化镍双层薄膜的光电致色特性

以金属钛为靶材、O2/N2/Ar混合气氛为溅射气体,在导电玻璃(ITO)表面磁控溅射一层薄膜,再经300-500℃退火处理制备了氮掺杂TiO2薄膜.采用X射线衍射(XRD)、X光电子能谱(XPS)、扫描电子显微镜(SEM)和紫外-可见吸收光谱等对薄膜的微观结构、光学特性和光电化学性能等进行了研究.进而采用化学沉积的方法在TiO2-xNx薄膜表面沉积上一层多孔NiO薄膜,研究表明,制备的ITO/TiO2-xNx/NiO双层薄膜具有明显的光电致色特性,400℃退火处理的氮掺杂TiO2薄膜具有最高的光电流响应,经氙灯照射1h后,薄膜从无色变成棕色,500nm波长处光透过率从79.0%下降至12.6%.     

In situ growth of CuS thin films on functionalized self-assembled monolayers using chemical bath deposition

Nano-structured CuS thin films were deposited on the functionalized -NH(2)-terminated self-assembled monolayers (SAMs) surface by chemical bath deposition (CBD). The deposition mechanism of CuS on the -NH(2)-terminated group was systematically investigated using field emission scanning electron microscope (FESEM), X-ray photoelectron spectroscope (XPS), UV-vis absorption. The optical, electrical and photoelectrochemical performance of CuS thin films incorporating with the X-ray diffraction (XRD) analysis confirmed the nanocrystalline nature of CuS with hexagonal crystal structure and also revealed that CuS thin film is a p-type semiconductor with high electrical conductivity (12.3Ω/□). The functionalized SAMs terminal group plays a key role in the deposition of CuS thin films. The growth of CuS on the varying SAMs surface shows different deposition mechanisms. On -NH(2)-terminated surfaces, a combination of ion-by-ion growth and cluster-by-cluster deposition can interpret the observed behavior. On -OH- and -CH(3)-terminated surfaces, the dominant growth mechanism on the surface is cluster-by-cluster deposition in the solution. According to this principle, the patterned CuS microarrays with different feature sizes were successfully deposited on -NH(2)-terminated SAMs regions of -NH(2)/-CH(3) patterned SAMs surface.     

Synthesis and deposition of nanostructured SnS for semiconductor-sensitized solar cell

Journal of Solid State Electrochemistry - Structural, electrical, and optical properties of SnS nanoparticles and films deposited by ultrasound-assisted chemical bath were studied. The SnS was...     

A solution growth technique for the preparation of copper (II) selenide thin films

A solution growth technique has been developed for the deposition of thin films of copper(II) selenide on glass substrate using a copper(II) salt solution, triethanolamine, ammonia, and sodium selenosulfate as the reacting agents. The material has been characterized through X-ray powder photography, optical absorption, and Hall measurements at room temperature. The films are found to be degenerate and p type with a Moss-Burstein shifted direct band gap of 2.14 eV.     

Chemical‐Bath‐Deposited Indium Oxide Microcubes for Solar Water Splitting

We fabricated films of cubic indium oxide (In₂O₃) by chemical bath deposition (CBD) for solar water splitting. The fabricated films were characterized by X‐ray diffraction analysis, Raman scattering, X‐ray photoelectron spectroscopy, and scanning electron microscopy, and the three‐dimensional microstructure of the In₂O₃ cubes was elucidated. The CBD deposition time was varied, to study its effect on the growth of the In₂O₃ microcubes. The optimal deposition time was determined to be 24 h, and the corresponding film exhibited a photocurrent density of 0.55 mA cm^?2. Finally, the film stability was tested by illuminating the films with light from an AM 1.5 filter with an intensity of 100 mW cm^?2.     

Electrodeposition of composite Ni–B coatings in a stirred heterogeneous system

The formation of composite electrochemical coatings of a nickel matrix with boron microparticles was investigated. Electrolytical nickel–boron layers were deposited on a paraffin-impregnated graphite electrode in a stirred heterogeneous system formed by a Watts-type nickel plating bath and dispersed boron powder particles. The polarisation behaviour of the composite plating bath as a function of the boron particle loading was examined. The effect of deposition conditions, as well as of the amount of boron powder in the plating bath on the boron content in the composite Ni–B coatings, was examined. The composite coating structure was established using scanning electron microscopy and light optical microscopy. The distribution of boron particles in the composite deposits was investigated by dynamic secondary ion mass spectrometry. The boron particles content was determined gravimetrically. The obtained results suggest that the content of incorporated boron particles increases with an increasing amount of boron in the plating bath. The potentiodynamic deposition method is demonstrated to be more suitable for production of composite coatings with a high content of boron particles than the potentiostatic one. Homogeneous distribution of boron particles in the nickel matrix without coagulation or sedimentation was associated with the electrochemical fabrication method in stirred heterogeneous systems.     

Ga对在AlN衬底上直接生长石墨烯的远程催化

通过镓(Ga)远程催化, 采用化学气相沉积(CVD)方法在氮化铝(AlN)衬底上直接生长石墨烯薄膜. 研究了生长温度、 催化剂距离对石墨烯生长及其光学性质和电学性质的影响规律. 结果表明, 在生长温度1070 ℃下可以制备厚度约为5层的石墨烯薄膜, Ga周围1.4 cm范围内可以得到厚度均匀的石墨烯薄膜. 通过透光率和方阻表征了石墨烯的光学和电学性质, 结果表明, 400~800 nm波长范围内石墨烯薄膜透光率可达90%以上, 方阻约为230 Ω/□. 第一性原理计算结果表明, 石墨烯仍保持金属性, AlN衬底对石墨烯有吸附掺杂作用, 可有效降低石墨烯的方阻, 改善石墨烯和衬底的电学接触.     

Ag活化的p型硅(111)表面化学镀Ag膜表面形貌研究

A method of electroless silver deposition on silver activated p-type silicon（111） wafer was proposed. The silver seed layer was deposited firstly on the wafer in the solution of 0.005 mol/L AgNO3 ＋0.06 mol/L HE Then the silver film was electrolessly deposited on the seed layer in the electroless bath of AgNO3＋NH3＋acetic acid＋NH2NH2 （pH 10.2）. The morphology of the seed layer and the silver films prepared under the condition of the different bath composition was compared by atomic force microscopy. The reflectance of the silver films with different thickness was characterized by Fourier transform infrared spectrometry. The experimental results indicate that the seed layer possesses excellent catalytic activity toward electroless silver deposition and rotating of the silicon wafer during the electroless silver deposition could lead to formation of the smoother silver film.     

Characterization of CuInS2 Thin Films with Different Cu/In Ratio

Thin films of CuInS₂ were grown on glass substrate by successive ionic layer adsorption and reaction method with different [Cu]/[In] ratios and annealed at 400 °C for 30 min. The crystal structure and grain sizes of the thin films were characterized by X-ray diffraction method. Atomic force microscopy was used to determine surface morphology of the films. Optical and electrical properties of these films were investigated as a function of [Cu]/[In]ratios. The electrical resistivity of CuInS₂ of thin films was determined using a direct current-two probe method in the temperature range of 300—470 K. It is observed that, the electrical resistivity values show a big decreasing with increasing [Cu]/[In] ratio. Hence, the [Cu]/[In] ratio in the solution can drastically affect the structural, electrical, and optical properties of thin films of CuInS₂.     

Photovoltaic Behaviour of Titanyl Phthalocyanine Thin Films and Titania Bilayer Films

Summary: Titanyl phthalocyanine (TiOPc) thin films were prepared using evaporation and surface polymerization by ion-assisted deposition (SPIAD) in a vacuum deposition system. These films were characterized by means of ultraviolet and X-ray photoelectron spectroscopy as well as UV/Vis absorption spectroscopy. Valence band and elemental content indicated that phthalocyanine electronic and chemical structures were largely preserved during SPIAD. Further, bilayer thin films of titania (TiO₂) and SPIAD TiOPc were prepared. TiO₂ film was deposited by reactive magnetron sputtering of TiO₂ target. Study of the structured samples was focused on the optical and electrical properties of the composite films. The films were characterized by non-contact photovoltage measurements and UV-Vis spectroscopy. These results suggest there is a possibility to use these bilayer thin films in photovoltaic solar cells, however further experiments to improve conductivity of the films will be required.