铜铟硫薄膜的固态硫化法制备及其性能研究

采用中频交流磁控溅射方法沉积Cu-In预制膜,并采用固态源蒸发硫化方法制备CuInS2薄膜。考察了硫源温度对CuInS2薄膜性能的影响。采用扫描电镜(SEM)和X射线能量色散谱仪(EDS)分别观察了薄膜的表面形貌和分析了薄膜的成分,采用X射线衍射(XRD)表征了薄膜的组织结构。结果表明,在硫源温度处于280℃到360℃范围之内时,制备的CuInS2薄膜都具有单一的黄铜矿型结构,颗粒均匀,晶粒大小约为1μm。     

硫化时间对于固态硫化CuInS_2薄膜性能影响

采用中频交流磁控溅射方法,在玻璃基底上沉积Cu-In预制膜,采用固态硫化法制备获得了CuInS2(CIS)吸收层薄膜。考察了硫化时间对于CIS薄膜结构、形貌以及禁带宽度影响。通过XRD分析了薄膜结构,通过SEM以及XRF分析薄膜表面形貌以及薄膜成分,通过近红外透过曲线得出薄膜禁带宽度。结果表明,在400℃硫化10,15,20,25,30 min下均能制得单一黄铜矿相CIS薄膜,并且具有(112)面择优取向。以上各硫化时间下,均能形成均匀且晶粒大小为1μm的CIS薄膜,薄膜禁带宽度约为1.10~1.22 eV之间。     

Cu/In原子比及硫化温度对于CuInS2薄膜性能影响

采用中频交流磁控溅射方法,在玻璃基底上沉积Cu-In预制膜,采用固态硫化法制备获得了CuInS2(CIS)吸收层薄膜.考察了预制膜Cu/In原子比及硫化温度对于CIS薄膜结构及禁带宽度影响.通过XRD及Raman光谱分析了薄膜结构,通过近红外透过曲线得出薄膜禁带宽度.结果表明,随着预制膜中Cu与In原子比(Cu/In)及硫化温度不断升高,薄膜CuAu(CA)相含量逐渐降低,黄铜矿(CH)相逐渐升高,薄膜结晶性逐渐改善.600℃以上硫化时薄膜中主要存在CH相CuInS2.薄膜禁带宽度随着预制膜中Cu/In原子比及硫化温度不断升高而升高,Cu/In原子比为1.05,硫化温度为500℃时薄膜禁带宽度可达1.40eV.     

热处理对CuInS2薄膜导电类型及光学特性的影响

真空蒸发在载玻片上沉积CuInS2薄膜(Cu、In、S原子配比为1∶0.1∶1.2).摸索CuInS2薄膜发生导电类型转换最有效的热处理条件,研究不同热处理工艺对CuInS2薄膜的结构、表面形貌、化学成分比和光学性能的影响.实验给出:沉积的薄膜进行360℃热处理30 min后,得到黄铜矿结构的CuInS2薄膜;SEN分析显示薄膜表面呈颗粒状较平整致密性略差,导电类型为N型,薄膜的本征吸收限为1.46eV,直接光学带隙Eg=1.38 eV.对薄膜进行370℃热处理20 min同样可得到N型CuInS2但含有少量的CuS2成分,薄膜表面致密性变好但粗糙度增大,本征吸收限发生红移为1.42 eV,Eg=1.40 eV.370℃,30 min热处理后可得到P型CuInS2薄膜,Eg=1.37 eV.制备的三种CuInS2薄膜的光吸收系数都在104 cm-1数量级以上.CuInS2薄膜中In或Cu元素含量大小,对薄膜的导电类型的变化起着决定性的作用,而薄膜中S和In元素的变化直接取决于热处理的条件.     

单源共蒸法制备CuInS2薄膜及特性分析

将单质Cu、In和S粉末按一定比例均匀混合,单源共蒸发沉积CuInS2薄膜.氮气保护对薄膜进行热处理.研究不同热处理条件对薄膜表面形貌、化学组分及电学特性的影响.XRD分析给出直接沉积的CuInS2薄膜为黄铜矿结构,整体性能较差.经400℃、20 min热处理后,CuInS2薄膜特性得到明显的改善,导电类型呈P型,体内元素化学计量比Cu:In:S=1:0.9:1.5接近标准值,Cu含量略多,电阻率为4.8× 10-2 Ω·cm,薄膜的直接光学带隙1.42 eV,光吸收系数105 cm-1.440℃、10 min热处理的薄膜,晶相结构没变但导电类型转为N型,元素化学计量比Cu:In:S=1:2.3:0.8,In元素过量,电阻率为1.3×10-2 Ω ·cm,光吸收系数104 cm-1,直接光学带隙1.39 eV.     

磁控溅射法制备的CZGe_xT_(1-x)S薄膜的光电性能研究

用先磁控溅射多层金属膜预置层后硫化的方法成功制备出CZGe_xT_(1-x)S薄膜,并主要研究了Ge含量对于该薄膜光电学性能的影响。分别采用X射线衍射仪、X射线能量色散谱仪、拉曼光谱仪、扫描电子显微镜,紫外-可见-近红外分光光度计和霍尔效应测量仪对不同Ge含量的CZGe_xT_(1-x)S薄膜的物相结构、元素比例、表面形貌、光学带隙以及电学性能进行了表征与分析。结果表明随着Ge含量的升高,晶粒尺寸不断长大,光学带隙从1.52上升至2.12 e V。同时,Ge替换Sn可减少薄膜内的缺陷,所制备的CZGe S薄膜的载流子浓度与迁移率分别为1.99×1018cm-3与9.712 cm2/Vs。     

离子束溅射沉积Fe/Si多层膜法合成β-FeSi_2薄膜的研究

采用离子束溅射沉积Fe/Si多层膜的方法在石英衬底上制备了β-FeSi2薄膜,研究了不同厚度比的Fe/Si多层膜对β-FeSi2薄膜的结构性能、形貌及光学性能的影响。结果表明,厚度比为Fe(2nm)/Si(7.4nm)的多层膜在退火后完全生成了β-FeSi2相,表面致密均匀,其光学带隙为0.84eV,能量为1.0eV光子的吸收系数105cm-1。     

氮气流量对CuInS2薄膜微结构的影响

采用硫化法制备出具有多晶结构的光吸收层CuInS2薄膜，研究了硫源处N2流量对CuInS2薄膜微结构的影响。利用SEM和EDS观察和分析了它们的表面形貌和成分，采用XRD表征了薄膜的结构。结果表明：N2流量增大到600ml／min制得具有黄铜矿结构且沿（112）晶向择优生长的CuInS2薄膜，晶粒尺寸为230nm。     

H2S气氛下硫化温度对Cu2ZnSnS4薄膜性能影响的研究

用磁控溅射法在玻璃衬底上沉积Zn/Sn/Cu预置层,然后再在H2S气氛下将其硫化制成Cu2ZnSnS4(CZTS)薄膜。研究了不同硫化温度(460,500,540和580℃)对CZTS薄膜性能的影响。采用X射线衍射、Raman、扫描电镜、能量色散谱和紫外-可见-近红外分光光度计表征薄膜的物相、表面形貌和光学性能。结果表明,在不同硫化温度下都成功制备了CZTS薄膜。当硫化温度为540℃时,制备的薄膜晶粒达到2μm,结晶性最好,表面致密光滑,而且它的吸收系数大于7×104cm-1,禁带宽度为1.49 e V。硫化温度较低(460℃)时,含有Cu2-xS杂质相,表面存在孔洞。而硫化温度较高(580℃)时,晶界处会产生微裂纹。     

电沉积制备CIS太阳能电池吸收层材料

在Cu衬底上用电沉积的方法沉积金属In,再通过硒蒸气硒化处理成功制备了CuInSe2薄膜.用X射线衍射(XRD)、扫描电镜(SEM)、X射线能谱(EDS)对制备的薄膜进行相组成、微观结构、表面形貌等分析,研究了制备工艺条件对薄膜性能的影响.结果表明:电沉积的In在低温热处理阶段与衬底Cu扩散形成Cu-In合金预制层,预制层在硒化阶段生成CuInSe2,合金中过量Cu生成CuSe表面层,未反应的In转变为Cu16In9,形成Cu衬底/Cu16In9/ CuInse2/CuSe结构.     

Pyrite (FeS2) thin films deposited by sol-gel method

Nanocrystalline pyrite (FeS₂) films were achieved by the sol-gel dip-coating process and sulfurization treatment. The microstructural, optical and electrical characteristics were investigated and the effect of sulfurization time on film properties was discussed. The XRD spectra show that FeS₂ film can be obtained for 1 h sulfurization and no other phase appears. The morphology of the precursor Fe₂O₃ films shows a porous and loose structure. However, with the sulfurization time increasing, the precursor films completely transformed into the pyrite films which have a compact and smooth structure. The pyrite films with a different sulfurization time have the optical absorption edges changed in the range of 0.90-0.99 eV. With the increase of sulfurization time, the carrier concentration increases and the carrier mobility decreases. It is speculated that crystallographic defects in the films could play an important role in film properties.     

Dependence of the properties of copper zinc tin sulfide thin films prepared by electrochemical deposition on sulfurization temperature

Copper zinc tin sulfide (CZTS, Cu₂ZnSnS₄) is a low band gap semiconductor that is attractive for use in solar cells. We investigated the dependence of the structure and properties of CZTS thin films on the temperature used to sulfurize precursor thin films composed of copper, zinc and tin fabricated by electrochemical deposition. The precursor films were sulfurized in a furnace with three zones, which allowed fine control of the sulfurization temperature between 250 and 400 °C. X-ray diffraction and Raman spectroscopic measurements confirmed that the films were composed of CZTS following sulfurization. The grain size and crystallinity of the films increased with sulfurization temperature. The composition of CZTS also varied with sulfurization temperature. The proportions of Cu and Zn increased while that of Sn decreased with increasing sulfurization temperature. Absorption and reflectance spectra revealed that the absorption coefficients and band gaps of the CZTS films varied with sulfurization temperature between 3–4.1 × 10⁴ cm^?1 and 1.4–1.53 eV, respectively. Solar cells containing CZTS sulfurized at 400 °C showed a maximum efficiency of 2.04 %, which was attributed to the higher crystallinity and larger grain size of CTZS compared with thin films sulfurized at lower temperatures. Our results show that control of sulfurization temperature is an important factor in optimizing the performance of CZTS thin films in solar cells.     

The optical and structural properties of polycrystalline Cu(In,Ga)(Se,S)2 absorber thin films

The pentenary compound semiconductor Cu(In,Ga)(Se,S)₂ is one of the most attractive materials for high-efficiency solar cells due to its tunable band gap to match well the solar spectrum. In this study, semiconducting Cu(In,Ga)(Se,S)₂ thin films were prepared by a classical two-step growth process, which involves the selenization and/or sulfurization of In/Cu–Ga precursor. During the precursor formation step metallic In/Cu–Ga alloys were deposited onto the Mo-coated soda-lime glass substrates by DC magnetron sputter process. The respective precursors were subsequently reacted with H₂Se and/or H₂S gasses, at elevated temperatures. By optimizing the selenization parameters, such as the gas concentrations, reaction time, reaction temperature, and the flow of H₂Se and H₂S, high quality, single phase pentenary films were obtained. The gallium and sulfur diffusion behaviors were found to depend strongly on the selenization/sulfurization profile. The surface morphology, phase structure, and composition of the layers were analyzed by scanning electron microscope, atomic force microscopy, X-ray diffraction, and electron diffraction spectroscopy. Photoluminescence measurements were performed to examine the optical properties of the films.     

Effect of sulfurization in hydrogen sulfide on the properties of Cu(In,Ga)Se2 thin-film absorbers

In this research Cu(In,Ga)Se₂ thin films were sulfurized in H₂S–Ar gas mixture with processing temperatures ranging from 400 to 550 °C and time ranging from 10 to 60 min. The change in crystal phases, microstructure and chemical compositions of the absorber layers after sulfurization were investigated by X-ray diffraction, high resolution TEM, scanning electron microscopy, Raman scattering spectrum, energy dispersive X-ray spectrometer. In the process of sulfurization, the crystallinity and sulfurization degree of the Cu(In,Ga)(S,Se)₂ films depend strongly on the sulfurization temperature. The ‘Cu–Au’ phase was found for samples grown at low sulfurization temperature and transformed to chalcopyrite-type phase at high sulfurization temperature. The Se–S vibration mode of Cu(S,Se) alloy was also observed in the Raman spectra.     

Control of metal salt ratio and MoS2 layer thickness in a Cu2ZnSnS4 thin film solar cell

Cu₂ZnSnS₄ (CZTS) absorber layers were prepared from copper acetate, zinc acetate, tin chloride, and thiourea in a solution of methanol, ethylenediamine, and ethanolamine using a sol–gel spin-coating method. Sol–gel precursor solutions were prepared with different metal salt ratios, and the effects on film growth, optical properties, and crystal properties of CZTS films were investigated. In addition, the role of sulfurization temperature on grain size of CZTS and formation of the MoS₂ layer at the CZTS and Mo interface were investigated. By changing the metal salt ratio in the precursor solution, a Zn-rich and Cu-poor condition in the CZTS film was obtained. By preparing Zn-rich and Cu-poor CZTS film with a thinner MoS₂ layer at a lower sulfurization temperature, the CZTS cell efficiency was improved, and a conversion efficiency of 1.22 % was obtained.     

Fabrication of Cu2ZnSnS4 absorber layers with adjustable Zn/Sn and Cu/Zn+Sn ratios

In this work Cu₂ZnSnS₄ (CZTS) thin films were successfully prepared by sulfurization of spin coated CuO + ZnO precursor films under Sn and S ambience with different time. Precursor films were synthesized using air-stable inks consist of carboxylate-capped metal oxide nanoparticles. The composition, microstructure and properties of CZTS thin films prepared with different sulfurization time were investigated using inductively coupled plasma-mass spectrometry, X-ray diffraction, scanning electron microscopy, Raman spectroscopy and UV–vis–NIR spectroscopy. The inductively coupled plasma-mass spectrometry results show that mole ratios of Zn/Sn and Cu/(Zn + Sn) in the films can be adjusted by controlling sulfurization time. A composition of Cu/Zn + Sn = ~0.8, and Zn/Sn = ~1.2 can be reached after sulfurizating with proper time. The influence of element composition change was also studied in our work using X-ray diffraction and Raman scattering. Two laser sources of 325 and 514 nm were involved in the Raman scattering analyze in order to identify secondary phases such as ZnS and Cu_2?xS. The as-prepared CZTS films with a composition of Cu/Zn + Sn = ~0.8, and Zn/Sn = ~1.2 exhibit a direct optical band gap about 1.45 eV.     

Structural and optical properties of sulfurized Cu2ZnSnS4 thin films from Cu–Zn–Sn alloy precursors

This study reports the preparation of Cu₂ZnSnS₄ (CZTS) thin films by magnetron sputtering deposition with a Cu–Zn–Sn ternary alloy target and sequential sulfurization. The effects of substrate temperatures on the structural, morphological, compositional as well as optical and electrical properties were characterized. The results showed the CZTS thin films prepared by sulfurization at substrate temperature of 570 °C yielded secondary phases along with CZTS compound. The relatively good properties of CZTS thin film were obtained after sulfurization at substrate temperature of 550 °C. This CZTS film showed compact structure with large grain size of 900 nm, direct optical band gap of 1.47 eV, optical absorption coefficient over 10⁴ cm^?1, resistivity of 4.05 Ω cm, carrier concentration of 8.22 × 10¹⁸ cm^?3, and mobility of 43.38 cm² V^?1 S^?1.     

Growth and Raman scattering characterization of Cu2ZnSnS4 thin films

In the present work we report the results of the growth, morphological and structural characterization of Cu₂ZnSnS₄ (CZTS) thin films prepared by sulfurization of DC magnetron sputtered Cu/Zn/Sn precursor layers. The adjustment of the thicknesses and the properties of the precursors were used to control the final composition of the films. Its properties were studied by SEM/EDS, XRD and Raman scattering. The influence of the sulfurization temperature on the morphology, composition and structure of the films has been studied. With the presented method we have been able to prepare CZTS thin films with the kesterite structure.     

Sulfurization time effects on the growth of Cu2ZnSnS4 thin films by solution method

Cu₂ZnSnS₄ (CZTS) films were obtained by sulfurizing (Cu, Sn) S/ZnS structured precursors prepared by a combination of the successive ionic layer absorption and reaction method and the chemical bath deposition method, respectively. The effect of sulfurization time on structure, composition and optical properties of these CZTS thin films was studied. The results of energy dispersive spectroscopy indicate that the annealed CZTS thin films are of Cu-poor and Zn-rich states. The X-ray diffraction studies reveal that Cu_2?x S phase exists in the annealed CZTS thin film prepared by sulfurization for 20 min, while the Raman spectroscopy analysis shows that there is a small Cu₂SnS₃ phase existing in those by sulfurization for 20 and 40 min. The band gap (E _g ) of the annealed CZTS thin films, which are determined by reflection spectroscopy, varies from 1.49 to 1.56 eV depending on sulfurization time. The best CZTS thin film is the one prepared by sulfurization for 80 min, exhibiting a single kesterite structure, dense morphology, ideal band gap (E _g  = 1.55 eV) and high optical absorption coefficient (>10⁴ cm^?1).     

Phase transformation in Cu2SnS3 (CTS) thin films through pre-treatment in sulfur atmosphere

In this study, Cu₂SnS₃ (CTS) thin films prepared by a two-step sulfurization process were characterized. Cu and Sn metallic layers were first deposited on glass substrates by sputtering and then annealed in-situ while in the sputtering chamber to obtain CuSn (CT) alloys. This was followed by a pre-treatment step at temperatures between 200 and 350 °C in presence of S vapors. Finally, a full sulfurization step was performed at 525 °C to obtain the desired CTS phase. CTS films were characterized using EDX, XRD, Raman spectroscopy, SEM, optical transmission and Van der Pauw methods. It was found that all CTS samples had Cu-poor chemical composition. XRD data revealed only diffraction peaks belonging to CTS structure after the full sulfurization step. Raman spectra of the samples showed that except for the CTS sample pre-treated at 250 °C (CTS-250), which displayed the tetragonal crystal system, the films were dominated by the monoclinic structure. SEM surface images showed dense and polycrystalline microstructure, CTS-200 sample exhibiting a more uniform morphology. Optical band gap values were found to be ranging from 0.92 to 1.19 eV. All samples showed p-type conductivity but the sample pre-treated at 350 °C had higher resistivity and lower carrier concentration values. Overall, the CTS layer prepared using the pre-treatment step at 200 °C exhibited more promising structural and optical properties for potential photovoltaic applications. This work demonstrated that it is possible to change the crystal structure of sulfurized CTS thin films through a pre-treatment step.