衬底对Cu(In,Ga)Se2薄膜织构的影响

分别在苏打石灰玻璃、Mo箔、无择优取向的Mo薄膜以及(110)择优取向的Mo薄膜四种不同衬底上,采用共蒸发工艺沉积约2μm厚的Cu(In,Ga)Se2薄膜,用X射线衍射仪测量薄膜的织构,研究衬底对Cu(In,Ga)Se2薄膜织构的影响.在以上四种衬底上沉积的Cu(In,Ga)Se2薄膜的(112)衍射峰强度依次逐渐减弱,(220/204)衍射峰从无到有且强度逐渐增强.在苏打石灰玻璃和Mo箔衬底上的Cu(In,Ga)Se2薄膜具有明显的(112)择优生长,而在(110)取向的Mo薄膜衬底上,Cu(In,Ga)Se2薄膜的织构为(220/204)取向.研究结果表明,只有(110)择优取向的Mo薄膜衬底对Cu(In,Ga)Se2薄膜(220/204)织构的形成有重要影响.     

Stage2沉积速率对低温生长CIGS薄膜特性及器件的影响

研究了三步法第二步沉积速率对低温生长Cu(In,Ga)Se₂薄膜结构、 电学特性和器件特性的影响. 通过改变第二步沉积速率发现, 提高沉积速率可以显著促进薄膜晶粒生长, 提高晶粒紧凑程度降低晶界复合, 同时有效改善两相分离现象, 提高电池的开路电压和短路电流, 有助于Cu(In,Ga)Se₂电池光电转换效率的提高. 但同时研究表明, 随着第二步沉积速率的增加, 会促进暂态Cu_2-xSe晶粒的生长, 引起Cu(In,Ga)Se₂薄膜表面粗糙度增大, 并阻碍Na向Cu(In,Ga)Se₂薄膜表面的扩散, 造成施主缺陷钝化效应降低, 薄膜载流子浓度下降和电阻率升高, 且过高的沉积速率会引起电池内部复合增加并产生分流路径, 造成开路电压下降进而引起电池效率恶化. 最终, 通过最佳化第二步沉积速率, 在衬底温度为420℃时, 得到最高转换效率为11.24%的Cu(In,Ga)Se₂薄膜太阳电池.     

低温超薄高效Cu(In,Ga)Se2太阳电池的实现

衬底温度保持恒定, 在Se气氛下按照一定的元素配比顺序蒸发Ga, In, Cu制备厚度约为0.7 μrm的Cu(In_0.7Ga_0.3)Se₂ (CIGS)薄膜. 利用X射线衍射仪分析薄膜的晶体结构及物相组成, 扫描电子显微镜表征薄膜形貌及结晶质量, 二次离子质谱仪测试薄膜内部元素分布, 拉曼散射谱 分析薄膜表面构成, 带积分球附件的分光光度计测量薄膜光学性能. 研究发现在Ga-In-Se预制层内, In主要通过晶界扩散引起Ga/(Ga+In)分布均匀化. 衬底温度高于450 ℃时, 薄膜呈现单一的Cu(In_0.7Ga_0.3)Se₂相; 低于400℃, 薄膜存在严重的Ga的两相分离现象, 且高含Ga相主要存在于薄膜的上下表面; 低于300 ℃, 薄膜结晶质量进一步恶化. 薄膜表层的高含Ga相Cu(In_0.5Ga_0.5)Se₂以小晶粒形式均匀分布于薄膜表面, 增加了薄膜的粗糙度, 在电池内形成陷光结构, 提高了超薄电池对光的吸收. 加上带隙值较小的低含Ga相的存在, 使电池短路电流密度得到较大改善. 衬底温度在550 ℃–350 ℃变化时, 短路电流密度J_SC是影响超薄电池转换效率的主要因素; 而衬底温度T_sub低于300 ℃时, 开路电压V_OC和填充因子FF降低已成为电池性能减退的主要原因. T_sub为350 ℃时制备的0.7 μm左右的超薄CIGS电池转换效率达到了10.3%. 关键词： 2薄膜')" href="#">Cu(In,Ga)Se₂薄膜 衬底温度 超薄 太阳电池     

等离子体活化硒对电沉积Cu-In-Ga金属预制层硒化的影响

使用等离子体活化硒源对电沉积制备的Cu-In-Ga金属预制层进行了硒化处理时, 发现等离子体功率对Cu(In_1-xGa_x)Se₂(CIGS)晶粒的生长有重要影响, 当等离子体功率为75 W时, 制备出单一Cu(In_0.7Ga_0.3)Se₂相的CIGS薄膜. 通过对不同衬底温度的等离子体活化硒源硒化的CIGS 薄膜进行了研究与分析, 并与普通硒化后的薄膜进行对比, 发现高活性硒在低温下会促进Ga-Se二元相的生成, 从而有利于Cu(In_0.7Ga_0.3)Se₂单相的生长. 对等离子体硒化后的CIGS薄膜进行了电池制备, 发现单相CIGS薄膜没有显著提高电池性能. 通过优化工艺, 所制备的CIGS电池效率达到了9.4%. 关键词： 0.7Ga_0.3)Se₂')" href="#">Cu(In_0.7Ga_0.3)Se₂ 电沉积 Cu-In-Ga金属预制层 等离子体活化硒     

硒化前后电沉积贫铜和富铜的Cu(In1-xGax)Se2薄膜成分及结构的比较

采用电沉积法获得了接近化学计量比的贫铜和富铜的Cu（In_1-xGa_x）Se₂（CIGS）预置层,研究比较了两种预置层及其硒化处理后的成分和结构特性.得到了明确的实验证据证明,硒化后富铜薄膜中的Cu_xSe相会聚集凝结成结晶颗粒分散在表面.研究表明：在固态源硒化处理后,薄膜成分基本不变;当预置层中原子比Cu/（In+Ga）<11时,硒化后薄膜表面存在大量的裂纹;而当Cu/（In+Ga） >12时,可以消除裂纹的产生,形成等轴状小晶粒;富铜预置层硒化时蒸发沉积少量In,Ga和Se后,电池效率已达到68%;而贫铜预置层硒化后直接制备的电池效率大于2%,值得进一步深入研究. 关键词： 1-xGa_x）Se₂薄膜')" href="#">Cu（In_1-xGa_x）Se₂薄膜 电沉积 硒化处理 贫铜或富铜薄膜     

直流磁控溅射厚度对Cu(Inx,Ga1-x)Se2背接触Mo薄膜性能的影响

采用直流磁控溅射工艺, 在一定条件下通过控制溅射时间, 在钠钙玻璃上制备了不同厚度的用于Cu(In_x, Ga_1-x)Se₂薄膜太阳电池背接触材料的Mo薄膜, 并利用X射线衍射 (XRD)、场发射扫描电子显微镜 (SEM)、四探针测试仪、台阶仪研究了厚度对溅射时间、薄膜微结构、电学性能及力学性能的交互影响. Mo薄膜的厚度与溅射时间呈线性递增关系; 随厚度的增大, Mo薄膜 (110) 和 (211) 面峰强均逐渐增大, 择优生长从(110)方向逐渐向 (211)方向转变, 方块电阻值只随 (110) 方向上的生长而急剧减小直到一特定值约2 Ω/⇑, 电导率随薄膜的 (110) 择优取向程度的降低而线性减小直到一特定值约0.96×10^-4 Ω·cm; Mo薄膜内部是一种多孔的长形簇状颗粒和颗粒间隙交织的结构, 并处于拉应力态, 其内部应变随薄膜厚度的增大而减小. 关键词： Mo薄膜 CIGS背接触 厚度 微结构     

不同衬底上Pb(Zr0.52Ti0.48)O3择优取向铁电薄膜的制备和研究

通过MOD法在Si(100)和Pt(111)/Ti/SiO₂/Si基片上制备出LaNiO₃ ( LNO)薄膜.再通过修 正的Sol-gel法，在Pt(111)/Ti/SiO₂/Si,LNO/Si(100)和LNO/Pt/Ti/SiO_{2< /sub>/Si三种衬底上 制备出具有择优取向的Pb(Zr0.52Ti0.48)O3铁电薄膜. 经XRD分析表明，L NO薄膜具有(100)择优取向的类钙钛矿结构；PZT薄膜均具有钙钛矿结构，且在Pt(111)/Ti/S iO2/Si衬底上的薄膜以(110)择优取向，在LNO/Pt/Ti/SiO2/Si和LN O/Si(100)衬底上的 薄膜以(100)择优取向.经场发射SEM分析和介电、铁电性能测试表明，在LNO/Si和LNO/Pt/Ti /SiO2/Si衬底上的PZT薄膜的平均粒径、介电常数以及剩余极化强度均比以Pt/T i/SiO2/Si为衬底的薄膜大. 关键词： 3}薄膜')" href="#">LaNiO₃薄膜 PZT铁电薄膜 择优取向 剩余极化强度     

PLD制备的Cu掺杂SnS薄膜的结构和光学特性

利用脉冲激光沉积(PLD)在玻璃衬底上制备了Cu掺杂SnS薄膜.靶材是由SnS和Cu₂S粉末混合压制而成(Cu和Sn的量比分别为0%、2.5%、5%、7.5%和10%).利用X射线衍射(XRD)、拉曼光谱仪(Raman)、原子力显微镜(AFM)、紫外-可见-近红外分光光度计(UV-Vis-NIR)、Keithley 4200-SCS半导体参数分析仪研究了Cu掺杂量对SnS薄膜的晶体结构、表面形貌、光学性质和电学性能的影响.结果表明:所制备的SnS薄膜样品沿(111)晶面择优取向生长, SnS :5%Cu薄膜的结晶质量最好且具有SnS特征拉曼峰.随着Cu掺杂量的增大, 平均颗粒尺寸逐渐增大.不同Cu掺杂量的薄膜在可见光范围内的吸收系数均为10⁵ cm^-1数 量级.SnS :5%Cu薄膜的禁带宽度E_g为2.23 eV, 光暗电导率比值为2.59.同时, 在玻璃衬底上制备了p-SnS :Cu/n-ZnS 异质结器件, 器件在暗态及光照的条件下均有良好的整流特性, 并具有较弱的光伏特性.     

Cu(In,Ga)Se2 薄膜在共蒸发"三步法"中的相变过程

CIGS薄膜的结晶相是制备高质量薄膜的关键问题. 本文采用共蒸发"三步法"工艺沉积Gu(In, Ga)Se₂ (CIGS) 薄膜, 通过X射线衍射仪 (XRD) 和X射线荧光光谱仪 (XRF)、扫描电镜 (SEM) 结合的方法详细研究了"三步法"工艺的相变过程, 并制备出转换效率超过15% 的 CIGS 薄膜太阳电池. 关键词： CIGS薄膜 共蒸发三步法 相变过程     

基于电子回旋共振-等离子体增强金属有机物化学气相沉积技术生长GaMnN稀磁半导体的研究

利用电子回旋共振-等离子体增强金属有机物化学气相沉积 (ECR-PEMOCVD)方法,采用二茂锰(Cp₂Mn)作为Mn源,高纯氮气作为氮源,三乙基镓(TEGa)作为Ga源,在蓝宝石(α-Al₂O₃)(0001)衬底上外延生长GaMnN稀磁半导体薄膜.反射高能电子衍射(RHEED)、X射线衍射(XRD)、原子力显微镜(AFM)表征了GaMnN薄膜的晶体结构和表面形貌.GaMnN薄膜均表现出良好的(0002)择优取向,表明制备的薄膜倾向于 关键词： GaMnN薄膜 稀磁半导体 铁磁性 居里温度     

A comparative study of solution based CIGS thin film growth on different glass substrates

CuIn_xGa_1−xSe_yS_2−y (CIGS) thin films were synthesized on glass substrates by a paste coating of Cu, In, and Ga precursor solution with a three-step heat treatment process: oxidation, sulfurization, and selenization. In particular, morphological changes of CIGS films for each heat treatment step were investigated with respect to the kinds of glass substrates: bare, Mo-coated, and F-doped SnO₂ (FTO) soda-lime glasses. Very high quality CIGS film with large grains and low degree of porosity was obtained on the bare glass substrate. Similar morphology of CIGS film was also acquired on the Mo-coated glass except the formation of an undesired Mo oxide interfacial layer due to the partial oxidation of Mo layer during the first heat treatment under ambient conditions. On the other hand, CIGS film with much smaller grains and higher degree of porosity was gained when FTO glass was used as a substrate, resulting in slight solar to electricity conversion behavior (0.20%). Higher power conversion efficiency (1.32%) was attained by the device with the CIGS film grown on Mo-coated glass in spite of the presence of a Mo oxide impurity layer.     

Texture and electronic activity of grain boundaries in Cu(In,Ga)Se2 thin films

The influence of different film textures on the electronic properties of polycrystalline Cu(In,Ga)Se₂ absorbers is studied by measuring the laterally resolved optoelectronic properties of differently textured Cu(In,Ga)Se₂ films with Kelvin probe force microscopy and cathodoluminescence. The grain boundaries in (112)- and (220/204)-textured films behave differently. The work-function profile measured with the Kelvin probe across a grain boundary in (112)-textured films shows a dip indicating positive charges at the grain boundaries. In panchromatic cathodoluminescence mappings in a transmission electron microscope, such grain boundaries appear dark, i.e. the strongly reduced luminescence indicates that the grain boundaries represent strong non-radiative recombination centers. In contrast, grain boundaries in (220/204)-textured films give rise to a dip or a step in the work function indicating slightly negative charge or neutrality. Cathodoluminescence is reduced at such grain boundaries, but less dramatically than in the (112)-textured case. However, when Na is present in the (220/204)-textured films, the grain boundaries are almost invisible in cathodoluminescence mappings. This strong passivating action of Na occurs only in the (220/204)-textured films, due to a particular grain-boundary population. In (112)-textured films and films without pronounced texture, this passivation effect is much less noticeable. PACS 73.50.Gr; 73.61.Ga; 78.60.Hk; 87.64.Dt     

Preparation and characterization of Cu(In,Ga)(Se,S)2 films without selenization by co-sputtering from Cu(In,Ga)Se2 quaternary and In2S3 targets

In this study, Cu(In,Ga)(Se,S)₂ (CIGSS) thin films were deposited onto a bi-layer Mo coated soda-lime glass by co-sputtering a chalcopyrite Cu(In,Ga)Se₂ (CIGS) quaternary alloy target and an In₂S₃ binary target. A one-stage annealing process was performed to form CIGSS chalcopyrite phase without post-selenization. Experimental results show that CIGSS films were prepared by the proposed co-sputter process via CIGS (70 W by radio frequency) and In₂S₃ (30 W by direct current) with a substrate temperature of 373 K, working pressure of 0.67 Pa, and one-stage annealing at 798 K for 30 min. The stoichiometry ratios of the CIGSS film were Cu/(In + Ga) = 0.92, Ga/(In + Ga) = 0.26, and Se/(S) = 0.49 that approached device-quality stoichiometry ratio (Cu/(In + Ga) < 0.95, Ga/(In + Ga) < 0.3, and (Se/S) ≈ 0.5). The resistivity of the sample was 14.8 Ω cm, with a carrier concentration of 3.4 × 10¹⁷ cm⁻³ and mobility of 1.2 cm² V⁻¹ s⁻¹. The resulting film exhibited p-type conductivity with a double graded band-gap structure.     

Characterization of Cu(In,Ga)Se2 thin films prepared by evaporationfrom ternary compounds

Thin films of Cu(In,Ga)Se₂ were fabricated by evaporation from ternary CuGaSe₂ and CuInSe₂ compounds for photovoltaic device applications and their properties were investigated. From XRF analysis, the Cu:(In+Ga):Se atomic ratio in all thin films was approximately 1:1:2. The Ga/(In+Ga) atomic ratio in the thin films changed linearly from 0 to 1.0 with increasing the [CGS]/([CGS]+[CIS]) mole ratio in the evaporating materials. However, for thin films prepared at the [CGS]/([CGS]+[CIS]) mole ratio above 0.4, the composition by EPMA analysis was not consistent with that by XRF analysis. The result of EPMA analysis showed that the surface of a thin film was Cu-rich. XRD studies demonstrated that the thin films prepared at the [CGS]/([CGS]+[CIS]) mole ratio under 0.2 had a chalcopyrite Cu(In,Ga)Se₂ structure and the preferred orientation to the 112 plane. On the other hand, XRD patterns of the thin films produced at the [CGS]/([CGS]+[CIS]) mole ratio above 0.6 showed the diffraction lines from a chalcopyrite Cu(In,Ga)Se₂ and a foreign phase. The separation of a peak was observed near 2θ=27°, indicative the graded Ga concentration in Cu(In,Ga)Se₂ thin film.     

低温生长Cu(InGa)Se2薄膜吸收层的掺钠工艺研究

在柔性聚酰亚胺衬底上低温制备Cu(In,Ga)Se₂薄膜太阳能电池, Na的掺入会改善电池特性, 但不同的掺Na工艺对Cu(In,Ga)Se₂薄膜和器件特性的改善机理不同. 本实验通过对比前掺NaF和后掺NaF工艺发现, 在前掺Na工艺下, 由于Na始终存在于Cu(In,Ga)Se₂薄膜生长过程中, Na存在于多晶 Cu(In,Ga)Se₂ 薄膜晶界处, 起到了扩散势垒的作用, 导致晶粒细碎、加剧两相分离, 同时减小了施主缺陷的形成概率; 而在后掺Na工艺下, 掺入的Na对薄膜的结构及生长不产生影响, 仅仅起到了钝化施主缺陷、改善薄膜缺陷态的作用. 同时, 研究表明, 后掺Na工艺中, NaF必须依靠外界能量辅助才能扩散进Cu(In,Ga)Se₂内部, 实验结果证实, 只有衬底温度达到350 ℃以上时, 掺入的NaF才能较好地改善薄膜特性. 最终经掺Na工艺的优化, 得到低温工艺制备的柔性聚酰亚胺衬底器件效率达10.4%.     

A non-selenization technology by co-sputtering deposition for solar cell applications

This work presents a novel method to form polycrystalline Cu(In(1-x)Ga(x))Se(2) (CIGS) thin film by co-sputtering of In─Se and Cu─Ga alloy targets without an additional selenization process. An attempt was also made to thoroughly elucidate the surface morphology, crystalline phases, physical properties, and chemical properties of the CIGS films by using material analysis methods. Experimental results indicate that CIGS thin films featured densely packed grains and chalcopyrite phase peaks of (112), (220), (204), (312), and (116). Raman spectroscopy analysis revealed chalcopyrite CIGS phase with Raman shift at 175 cm(-1), while no signal at 258 cm(-1) indicated the exclusion of Cu(2-x)Se phase. Hall effect measurements confirmed the polycrystalline Cu(In,Ga)Se₂ thin film to be of p type semiconductor with a film resistivity and mobility of 2.19×10(2) Ω cm and 88 cm(2)/V s, respectively.     

Correlation of structure parameters of absorber layer with efficiency of Cu(In,Ga)Se<Subscript>2</Subscript> solar cell

Polycrystalline Cu(In, Ga)Se₂ with Ga-content x=Ga/(In+Ga) ranging from 0.0 (CuInSe₂) to 1.0 (CuGaSe₂) in heterojunction thin film solar cells were grown by multi-source evaporation. Solar cells with a highest efficiency of η=15.3% need a composition of x≈0.2. At this composition, the c/a ratio of the lattice constants for the tetragonal lattice equals c/a=2, indicating ideal tetragonality. These results suggest that low electronic defect densities occur at x≈0.2, due to the smallest possible crystallographic distortion of the tetragonal lattice at this composition. Cells with high efficiencies require grain sizes above 145 nm and a high preferred orientation (P₂₀₄/P₂₂₀ pole density ratio) for the grains.     

Mo Back Contact for Flexible Polyimide Substrate Cu（In,Ga）Se2 Thin-Film Solar Cells

A dc magnetic sputtering process is applied to growth of a Mo back. contact layer onto the flexible polyimide （PI） and rigid soda-lime glass （SLC） substrates. The structural and electrical properties of the Mo layer coated on the two kinds of substrates are investigated by x-ray diffraction （XRD） and Hall effect measurements. The results show that the Mo layer on SLG indicate more better crystal quality and lower resistivity than that on the PI sheets. In contrast to the SLG substrate, the resistivity of the Mo layer on PI is increased by the vacuum annealing process at the substrate temperature of 450℃ under Se atmosphere, which is attributed to the cracked Mo layer induced by the mismatch of the coefficient of thermal expansion between PI and Mo material. The Cu（In,Ga）Se2 （CIGS） solar cells based on the PI and SLO substrates show the best conversion efficiencies of 8.16% and 10.98% （active area, 0.2cm^2）, respectively. The cell efficiency of flexible CIGS solar cells on PI is limited by its relatively lower fill factor caused by the Mo back contact.     

Preparation of Cu（In,Ga）Se2 Thin Film Solar Cells by Selenization of Metallic Precursors in an Ar Atmosphere

Cu（In, Ga）Se2 thin films are deposited on Mo-coated glass substrates by Se vapour selenization of sputtered metallic precursors in the atmosphere of Ar gas flow under a pressure of about 10 Pa. The in situ heat treatment of as-grown precursor leads to the formation of a better alloy. During selenization, the growth of CuInSe2 phase preferably proceeds through Se-poor phases as CuSe and InSe at relatively low substrate temperature of 250℃, due to the absence of In2Se3 at intermediate stage at low reactor pressure. Subsequently, the Cu（In,Ga）Se2 phase is produced by the reactive diffusion of CuInSe2 with a Se-poor GaSe phase at high temperature of up to 560℃. The final film exhibits smooth surface and large grain size. The absorber is used to fabricate a glass/Mo/Cu（In, Ga）Se2/CdS/ZnO cell with the total-area efficiency of about 7%. The low open-circuit voltage value of the cell fabricated should result from the nonuniform distribution of In and Ga in the absorber, due to the diffusion-controlled reaction during the phase formation. The films, as well as devices, are characterized.