Indium selenide microrod films: chemical bath deposition from acidic bath

Films of indium selenide was deposited onto glass and indium tin oxide coated glass substrates in acidic medium using chemical bath deposition at room temperature. Indium sulphate and sodium selenosulphate were used as precursors of In³⁺ and Se^2?, respectively. The structural, surface morphological and optical properties of the deposited films were studied. Diffractograms in structural study revealed the deposited material is In₂Se₃ films. Controlled bath conditions resulted in the evolution of the In₂Se₃ microrod-like morphology. The optical band gap of the film was found to be 1.7 eV.     

化学水浴法制备ZnS薄膜光学性能

利用薄膜分析系统测量不同沉积时间制备的ZnS薄膜透射谱,通过分析薄膜透射谱,来确定ZnS薄膜光学常数和禁带宽度.实验结果表明,在线性生长阶段,薄膜的沉积速率大约为1 nm/min,具有很好的线性关系,沉积0.5 h的ZnS薄膜在可见光范围内光透过率为82%左右.     

Influence of the deposition parameters on the properties of orthorhombic SnS films by chemical bath deposition

Orthorhombic stannous sulfide (SnS) films were prepared by chemical bath deposition in which stannous dichloride (SnCl₂), ammonium citrate (C₆H₅O₇(NH₄)₃) and sodium thiosulfate (Na₂S₂O₃) were used as tin source, chelating reagent and sulfur source, respectively. The influence of the deposition temperatures and the concentration ratios of Na₂S₂O₃/SnCl₂ on the morphologies, compositions and electrical and optical properties of the SnS films were investigated. The results show that the compactness of the SnS films gets worse when the deposition temperature increases, while the compactness of the films gets better when the concentration ratio of Na₂S₂O₃/SnCl₂ increases. The compositions of the films (the molar ratio of S/Sn ranges from 46.7:53.3 to 48.9:51.1) are all close to the stoichiometric ratio of SnS, and the molar ratio of S/Sn in the films increases as the deposition temperature and the concentration ratio of Na₂S₂O₃/SnCl₂ increase. The optical bandgaps of the SnS films are in the range of 1.01 eV-1.26 eV. The dark conductivities and photo conductivities of the SnS films all increase as the deposition temperature and the concentration ratio of Na₂S₂O₃/SnCl₂ increase.     

Multiple dip deposition of CdS films prepared by oscillating chemical bath

Highly oriented CdS thin films with thicknesses greater than 1 μm were deposited using the oscillating chemical bath deposition technique with multiple dips at 75 °C, and from 15 to 75 min as deposition times. Samples with different thicknesses were deposited by repeating the chemical deposition process one, two and three times. All CdS films present the α-greenockite hexagonal structure with (002) as the preferential orientation. Band-gap energy values ranged from 2.35 to 2.42 eV, being the smaller value for the two dip processes. Energy dispersion spectroscopy measurements show good stoichiometry of the CdS films with 4.3 at.% as the maximum Cd variation.     

CdS thin films growth by ammonia free chemical bath deposition technique

Cadmium Sulfide CdS thin films were deposited by chemical bath deposition technique using ethanolamine as complexing agent instead of commonly used ammonia to avoid its toxicity and volatility during film preparation. In order to investigate the film growth mechanism samples were prepared with different deposition times. A set of substrates were dropped in the same bath and each 30 minutes a sample is withdrawn from the bath, by this way all the obtained films were grown in the same condition. The films structure was analyzed by X rays diffraction. In early stage of growth the obtained films are amorphous, with increasing the deposition time, the films exhibits a pure hexagonal structure with (101) preferential orientation. The film surface morphology was studied by atomic force microscopy. From these observations we concluded that the early growth stage starts in the 3D Volmer-Weber mode, followed by a transition to the Stransky-Krastanov mode with increasing deposition time. The critical thickness of this transition is 120 nm. CdS quantum dots were formed at end of the film growth. The optical transmittance characterization in the UV-Visible range shows that the prepared films have a high transparency ranging from 60 to 80% for photons having wavelength greater than 600 nm.     

化学水浴沉积时间对CdS薄膜性质的影响

采用CBD法在醋酸镉溶液体系中制备CdS半导体薄膜,通过XRD、XRF、SEM和光学透过率谱等测试手段研究了沉积时间对CdS薄膜沉积过程和性质的影响.结果表明,随着沉积时间的增加,薄膜增厚;S/Cd原子比增加,但都为富Cd的CdS薄膜;XRD研究表明,薄膜结构由立方、六方混合相向立方相转变,(111)方向成为择优生长方向;SEM研究表明,随沉积时间增加,薄膜变致密,薄膜表面出现的白色附着颗粒增多,尺寸增大;沉积时间对薄膜的光学性质也有很大的影响,随着沉积时间的增加薄膜透过率减小,而禁带宽度值增大.     

CdS thin films doped with metal-organic salts using chemical bath deposition

CdS thin films doped with metal-organic salts were grown on glass substrates at 90 °C by the chemical bath deposition technique. Metal-organic salts such as zinc acetate, chromium acetylacetonate, ammonium fluoride, aluminum nitrate, tin acetate and indium acetate were used. The chemical bath was prepared with cadmium acetate, ammonium acetate, thiourea and ammonium hydroxide. In the case of un-doped films, the S/Cd ratio was varied by changing the thiourea in the range 1-12. The best optical, structural and electrical properties were found for S/Cd = 2. The doped films were prepared by always keeping the ratio S/Cd constant at 2. The band gap (E_g) of doped and un-doped films was evaluated from transmittance spectra, where films with lower sulfur concentration exhibited higher E_g. X-ray analysis showed that both un-doped and doped films were polycrystalline with preferential orientation along the (111) direction and with the zincblende structure in all cases. The dark electrical results showed that CdS doped with Zn (1 at.%) exhibited the lowest resistivity values of 10 Ω cm.     

Investigation of the ZnSxSe1-x thin films prepared by chemical bath deposition

The ZnS_xSe_1?x thin films were prepared by chemical bath deposition technique on glass substrates. The composition ‘x’ was varied from 0 to 1 by changing the concentration of thiourea and sodium selenosulphate in the precursors. The morphology, structural and optical properties of the ZnS_xSe_1?x thin films were characterized by energy dispersive spectrometer, scanning electron microscopy, X-ray diffraction and UV-Vis spectrophotometer. The results reveal that the ZnS_xSe_1?x films are cubic zinc blende structure for x = 0, 0.19, 0.25, and amorphous for x = 0.75, 1. The optical band gap of the ZnS_xSe_1?x films increase from 2.88 to 3.76 eV when the value of ‘x’ increases from 0 to 1. The growth mechanism of the ZnS_xSe_1–x films was discussed.     

Preparation and characterization of ZnS thin films by the chemical bath deposition method

ZnS thin films prepared on quartz substrates by the chemical bath deposition (CBD) method with three type temperature profile processes have been investigated by X-ray diffraction, scanning electron microscope, energy dispersive X-ray analysis and light transmission. One is a 1-step growth process, and the other is 2-steps growth and self-catalyst growth processes. The surface morphology of CBD-ZnS thin films prepared by the CBD method with the self-catalyst growth process is flat and smooth compared with that prepared by the 1-step and 2-steps growth processes. The self-catalyst growth process in order to prepare the particles of ZnS as initial nucleus layer was useful for improvement in crystallinity of ZnS thin films prepared by CBD. ZnS thin films prepared by CBD method with self-catalyst growth process can be expected for improvement in the conversion efficiency of Cu(InGa)Se₂-based thin film solar cells by using it for the buffer layer.     

Structural analysis of indium sulphide thin films elaborated by chemical bath deposition

X-ray diffraction and scanning electron microscopy show that the crystalline state of indium sulphide thin films, elaborated by chemical bath deposition technique on various substrates, is strongly affected by deposition parameters (deposition time t_D, pH solution and thioacetamide concentration), as well as by annealing treatment.We show that β-In₂S₃ thin films grown on glass substrate during t_D=60 min, and annealed under nitrogen at 400 °C during 1 h are well crystallized according to the cubic structure with the preferential orientation (610). They have a good homogenity and crystallinity.     

Improved efficiency of the chemical bath deposition method during growth of ZnO thin films

Chemical bath deposition (CBD) is an inexpensive and low temperature method (25-90 °C) that allows to deposit large area semiconductor thin films. However, the extent of the desired heterogeneous reaction upon the substrate surface is limited first by the competing homogeneous reaction, which is responsible for colloidal particles formation in the bulk solution, and second, by the material deposition on the CBD reactor walls. Therefore, the CBD method exhibits low efficiency in terms of profiting the whole amount of starting materials. The present work describes a procedure to deposit ZnO thin films by CBD in an efficient way, since it offers the possibility to minimize both the undesirable homogeneous reaction in the bulk solution and the material deposition on the CBD reactor walls. In a first stage, zinc peroxide (ZnO₂) crystallizing with cubic structure is obtained. This compound shows a good average transparency (90%) and an optical bandgap of 4.2 eV. After an annealing process, the ZnO₂ suffers a transformation toward polycrystalline ZnO with hexagonal structure and 3.25 eV of optical bandgap. The surface morphology of the films, analyzed by atomic force microscope (AFM), reveals three-dimensional growth features as well as no colloidal particles upon the surface, therefore indicating the predominance of the heterogeneous reaction during the growth.     

Some physical properties of Sn-doped CdO thin films prepared by chemical bath deposition

Undoped and Sn-doped CdO thin films were prepared by the chemical bath deposition method by means of a procedure that improves the deposition efficiency. All as-grown films were crystallized in the cubic structure of cadmium peroxide (CdO₂) and transformed into CdO with a cubic structure after an annealing process. The as-grown films have a high resistivity (> 10⁶ Ω cm) and an optical bandgap around 3.6 eV. Undoped CdO displays an optical bandgap around 2.32–2.54 eV and has an electrical conductivity of 8 × 10^− 4 Ω cm. The Sn incorporation into CdO produces a blue shift in the optical bandgap (from 2.55 to 2.84 eV) and a decrease in the electrical conductivity.The deposition procedure described here gives colloid-free surface thin films as indicated by the surface morphology analysis.     

化学水浴中氨浓度对沉积ZnS薄膜的影响

用化学水浴法在玻璃衬底上沉积ZnS薄膜。采用XRD、SEM、nkd-薄膜分析系统对薄膜的形貌、结构和光学性能进行了分析，结果表明：当氨浓度〈1．50mol／L，可获得白点较少、平整性较好的非晶ZnS薄膜，在红移方向上很长的波段内透过率较好，可达95％以上，禁带宽度为3．81eV，折射率随波长的增加而减小，从2．32变化到1．92。有关化学水浴ZnS薄膜折射率的报道极少；当氨浓度〉1．50mol／L时，薄膜白点增多，易龟裂和剥落，结构是立方闪锌矿。     

Effects of complexing agent on CdS thin films prepared by chemical bath deposition

CdS films have been prepared by chemical bath deposition (CBD) without stirring using weak and strong complexing agents, i.e., ammonia and ethylenediaminetetraacetic acid (EDTA). The optical, structural, and morphological properties of chemical bath deposited CdS films have been investigated. When the complexing agent is ammonia, five peaks in the X-ray diffraction (XRD) patterns from the CdS film, respectively, correspond to the interplanar spacing of 3.5498, 3.3429, 3.1449, 2.0574, and 1.7487 Å, which are definitely ascribed to hexagonal structure; unfortunately, this hexagonal CdS film is with poor morphology and its optical property in the visible region is not desirable for the solar cells. While, when the complexing agent is EDTA, three diffraction peaks in the XRD patterns from the CdS film, respectively, correspond to the interplanar spacing of 3.1164, 2.6716, and 1.8507 Å, indicating that the film is of a cubic structure. Furthermore, the CdS film has good morphology and its optical property in the visible region is compliant to the requirements of solar cells.     

Structural and optical properties of CdS thin films grown by chemical bath deposition

Cubic cadmium sulphide (CdS) thin films with (111) preferential orientation were prepared by chemical bath deposition (CBD) technique, using the reaction between NH₄OH, CdSO₄ and CS(NH₂)₂. The films properties have been investigated as a function of bath temperature and deposition time. Structural properties of the obtained films were studied by X-ray diffraction analysis. The structural parameters such as crystallite size have been evaluated. The transmission spectra, recorded in the UV visible range reveal a relatively high transmission coefficient (70%) in the obtained films. The transmittance data analysis indicates that the optical band gap is closely related to the deposition conditions, a direct band gap ranging from 2.0 eV to 2.34 eV was deduced. The electrical characterization shows that CdS films' dark conductivities can be controlled either by the deposition time or the bath temperature.     

Formation of CuxS thin films through a chemical bath deposition process

A method for the preparation of Cu_xS thin films through chemical bath deposition is described. The films have been formed on a glass substrate from a bath containing a triethanolamine complex of copper ions, ammonia and thiourea. The stoichiometry and optical characteristics of the films have been determined. This method has been used to form a solar cell through deposition of Cu_x S on a CdS substrate. The I–V characteristics of the cell are reported.     

Effect of pH on the properties of ZnS thin films grown by chemical bath deposition

Zinc sulphide thin films have been deposited on glass substrates using the chemical bath deposition technique. The depositions were carried out in the pH range of 10 to 11.5. Structure of these films was characterized by X-ray diffraction and scanning electron microscopy. Optical properties were studied by spectrophotometric measurements. Influence of the increased pH value on structural and optical properties is described and discussed in terms of transmission improvement in the visible range. Transmission spectra indicate a high transmission coefficient (70%). The direct band gap energy is found to be about 3.67 eV for the films prepared at pH equal to 11.5.     

化学沉积参数对CdS薄膜前驱物利用率的影响

采用化学水浴法,在醋酸镉、硫脲、氨水、醋酸铵的体系中制备CdS薄膜,设计L2556正交实验,研究了各沉积参数对前驱物利用率的影响.结果表明,随前驱物醋酸镉、硫脲各自浓度的增加,其自身的利用率下降,但另一方的利用率上升.前驱物的利用率随络合剂醋酸铵浓度的增加先增大后减小,随氨水浓度的增加先减小后增大;其利用率随反应条件温...