化学水浴法制备ZnS薄膜及其光学性能

以酒石酸与柠檬酸钠为络合剂,采用化学水浴法(CBD)沉积ZnS薄膜.利用X射线衍射仪(XRD)、X射线能谱仪(EDAX)、扫描电镜(SEM)、紫外-可见分光光度计(UV-Vis)研究ZnS薄膜的结构、组成、形貌及光学性能,利用透射光谱计算ZnS薄膜的光学禁带宽度(Eg).结果表明:ZnS薄膜呈立方相晶体结构,经过300℃熟处理1h的ZnS薄膜原子比为Zn:S=1:0.85,表面均一致密,在可见光区的平均透射率达到80%,光学禁带宽度为3.74ev,适合作为太阳能电池过渡层.     

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.     

温度对化学水浴法制备ZnS薄膜的影响

采用化学水浴法在玻璃上制备了太阳能电池中的ZnS缓冲层。采用SEM、EDS、XRD和nkd-分光光度计等手段研究了水浴温度对ZnS薄膜的表面形貌、结构和光学性能的影响。结果表明,升高温度不能明显改变薄膜的结晶性、形貌和沉积生长方式,能否成膜与温度的关系也不大,但成膜速率对温度的依赖性较大。随温度的升高,薄膜的透过率先减小后增大,反射率则先增大后减小。对同一试样而言,透过率和反射率对应较好。当温度为70℃时,可制得禁带宽度为3.83eV、符合化学计量比、平整的非晶ZnS薄膜。     

三元体系化学水浴法制备ZnS薄膜结晶性能的研究

太阳薄膜电池ZnS缓冲层一般以氨水为主络合剂、水合肼为辅助络合剂二元络合体系化学水浴法制备。实验发现以氨水为主络合剂、水合肼和柠檬酸为辅助络合荆三元体系制备的ZnS薄膜质量明显要比氨水、水合肼二元体系的ZnS薄膜好。薄膜表面更加光亮、平整，光透过率能得到明显提高。从实验现象和测试结果来看，随柠檬酸浓度增加，在反应溶液中无定形态白色沉淀明显减少，ZnS薄膜结晶性能也得到明显提高，ZnS薄膜光透过率升高。柠檬酸浓度为0．15mol／L时，薄膜光透过率达到85％左右，完全满足太阳能电池的要求；继续增加柠檬酸的量，薄膜光透过率趋于一致，光透过率略有回落。     

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。     

化学超声水浴沉积法制备CdSe薄膜及其性能的研究

以CdCl2.2.5H2O为镉源,Na2SeSO3为硒源,柠檬酸钠为络合剂,采用化学超声水浴沉积法制备了CdSe薄膜,用XRD、UV-Vis、SEM等方法进行表征,结果表明,所制备的薄膜为n型半导体,在可见光区有一定的吸收,可以获得较好的光电流。应用化学超声水浴沉积法制备CdSe薄膜的优化条件为：络合剂比例1：1.5、镉与硒浓度比例2.5：1、PH值10、沉积时间2.5h、退火温度350℃。     

水溶性ZnS量子点的共沉淀法制备、 表征及其光学性能

以硫化钠和乙酸锌为反应物,3-巯基丙酸为表面包覆剂,利用共沉淀法制备了水溶性ZnS量子点。并采用X射线衍射仪、透射电子显微镜和荧光分光光度计等对样品的结构、形貌、粒径和光学性能进行了表征。结果表明:所得样品为ZnS立方型闪锌矿结构,量子点的形状呈不规则球形,粒径主要集中在4.8nm左右;样品在585～590nm之间出现了黄色荧光发射波峰。同时,利用红外光谱对ZnS量子点的合成机理进行了初步分析。     

ZnS薄膜的制备及性能研究

用射频溅射法在Si基片和石英基片上分别制备了490nm厚的ZnS薄膜,并在不同温度下进行退火处理.微结构分析表明:退火后的ZnS薄膜均呈多晶状态,晶体结构为立方闪锌矿结构的β-ZnS;随着退火温度的升高,薄膜的平均晶粒尺寸逐渐增大,由20℃的10.91nm增大到500℃的15.59nm,晶格常数在不同退火温度下均比标准值0.5414nm稍小.应力分析表明:退火后的ZnS薄膜应力减小,400℃时分布较均匀,平均应力为1.481×108Pa,应力差为1.939×108Pa.且400℃前为张应力,400℃以后转变为压应力.光学分析表明,随着退火温度的升高,ZnS薄膜的透过率增强,吸光度减弱.     

两步法制备SnS光电薄膜及其性能

用两步法在ITO玻璃基片上制备SnS薄膜,即先在ITO玻璃基片上热蒸发一层Sn膜,然后在一定的温度和时间下在真空系统中进行硫化.在优化工艺条件下制备出附着力好的薄膜,通过扫描电子显微镜、X射线衍射、分光光度计等手段观察和分析测试,表明该薄膜是正交结构的SnS,薄膜表面致密,颗粒大小均匀.根据薄膜的反射光谱和透射光谱,计算得到其在吸收边的吸收系数α>5×104cm-1,直接带隙Eg=1.48eV,适合于作为太阳能电池的吸收层材料.     

络合剂对化学水浴沉积 ZnS薄膜的影响

采用不同络合剂化学水浴沉积ZnS薄膜,应用台阶仪、SEM、XRD、波谱仪等手段测定了ZnS薄膜的厚度、表面、物相结构及透过率等.结果表明,氨水体系沉积薄膜速度明显慢于另外两种体系,沉积的ZnS薄膜都为立方结构.柠檬酸钠体系沉积的ZnS 薄膜结晶和透过率最佳,但薄膜表面缺陷较多;氨水-联氨体系沉积的ZnS薄膜表面质量最佳,结晶和透过率也较好;氨水体系沉积的ZnS薄膜质量较差.用3种体系沉积的ZnS薄膜用于制备铜铟镓硒Cu(In,Ga)Se2太阳电池,氨水和氨水-联氨体系沉积的ZnS薄膜制备的电池转换效率明显高于柠檬酸钠体系沉积的ZnS制备的太阳电池.     

Chemical bath deposition of SnS thin films on ZnS and CdS substrates

We illustrate that Tin sulfide (SnS) thin films of 110–500 nm in thickness may be deposited on ZnS and CdS substrates to simulate the requirement in developing window-buffer/SnS solar cells in the superstrate configuration. In the chemical bath deposition reported here, tin chloride and thiosulfate are the major constituents and the deposition is made at 25 °C. In a single deposition, film thickness of 110–170 nm is achieved and in two more successive depositions, the film thickness is 450–500 nm. The thicker films are composed of vertically stacked flakes, 100 nm across and 10–20 nm in thickness. The Sn/S elemental ratio is ~1 for the films 110–170 nm in thickness, but it slightly increases for thicker films. The crystalline structure is orthorhombic, similar to the mineral herzenbergite, and with crystallite diameters 13 nm (110–170 films) and 16 nm (450–500 nm films). The Raman bands at 94, 172 and 218 cm^?1 further confirm the SnS composition of the films. The optical band gap of SnS is 1.4–1.5 eV for the thinner films, but is 1.28–1.39 eV for the thicker films, the decrease being ascribed to the increase in the crystallite diameter. Uniform pin-hole free SnS thin films were successfully grown on two different substrates and can be applied in solar cell structures.     

Structural,optical, photocurrent and mechanism-induced photocatalytic properties of surface-modified ZnS thin films by chemical bath deposition

ZnS thin films were prepared by chemical bath codeposition using ZnSO₄–ZnCl₂ or Zn(CH₃COO)₂–ZnCl₂ as zinc ion sources. The presence of SO₄ ^2? favors the heterogeneous growth of ZnS thin film. The coexistence of two zinc salts impedes the formation of homogeneous precipitation and improves the growth rate of ZnS film. XRD and HRTEM results show that all the samples exhibit the cubic structure. EDS analysis shows that Zn/S atom ratios from the codeposition are closer to 1:1 than those deposited from a single zinc salt, and ZnS thin films of S3 and S7 are very uniform without stirring. FTIR reveals that –NH₂ group as a surface modifier is adsorbed on the surface of ZnS nanoparticles. Raman spectra further reveal that S3, S4 and S7 form the ZnS films, and ZnO phase is present in short or middle range of the S6 nanocrystal, indicating that different amounts of zinc salts affect the structure of ZnS films significantly after three 2.5 h deposition cycles. The grain sizes determined by FESEM are inversely proportional to RMS determined by AFM. The band gap values of ZnS thin films agree well with the results of HRTEM. The photocurrent responses of different samples are similar, indicating that different amounts of zinc salts have little effect on the photocurrent of ZnS films. The photocatalytic performance of S6 and S8 is much better than that of S1–S5. S6 decomposes 65 % of methyl orange within 3 h, and its K value is 4.78 × 10^?1 h^?1. The photocatalytic performance is induced by the growth mechanism, which determines the grain size of ZnS thin film. The tendency of grain sizes of ZnS films agrees well with that of photocatalytic performance, especially under the clusters by clusters deposition.     

Cobalt sulphide thin films: Chemical bath deposition,growth and properties

In the present report synthesis of CoS thin films was carried out by a modified liquid phase chemical growth process. Dark green coloured CoS thin films with hexagonal wurtzite polycrystalline structure and average grain size of ≈ 15 nm were deposited. Surface morphology reveals a randomly oriented network of elongated thread like grains. The absorption coefficient of the CoS thin film is high (α ≈ 10⁴–10⁵ cm^? 1) and a direct band gap of 1.13 eV has been observed. n-type conduction is found in the deposited films which can be attributed to the lack of stoichiometry.     

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.     

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.     

Size dependent optical characteristics of chemically deposited nanostructured ZnS thin films

ZnS thin films of different thicknesses were prepared by chemical bath deposition using thiourea and zinc acetate as S²⁻ and Zn²⁺ source. The effect of film thickness on the optical and structural properties was studied. The optical absorption studies in the wavelength range 250–750 nm show that band gap energy of ZnS increases from 3·68–4·10 eV as thickness varied from 332–76 nm. The structural estimation shows variation in grain size from 6·9–17·8 nm with thickness. The thermoemf measurement indicates that films prepared by this method are of n-type.