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。     

溅射气压对磁控溅射Mo背电极层形貌与结构的影响

采用直流磁控溅射法在溅射气压为0.1~1.0Pa下制备了金属Mo膜。用扫描电子显微镜(SEM)和原子力显微镜(AFM)对单层Mo膜的表面、断面形貌和粗糙度进行了分析与表征;用X射线衍射(XRD)研究了气压对Mo膜晶粒尺寸和薄膜应力应变的影响;用SEM观察了双层和三层Mo背电极层的表面形貌。结果表明,溅射气压升高,表面颗粒由细长变得圆润,均方根粗糙度升高,其值介于1.32~4.81nm之间;Mo膜的晶粒尺寸随气压的升高而降低,其值介于27.2~11.7nm之间;溅射气压为0.2Pa和0.3Pa时制备的Mo膜显现为张应力;将双层Mo背电极表面制备0.7Pa的Mo层后,表面更加圆润,孔隙增多。     

钼网表面MoSi2涂层的制备及其1500℃高温氧化性能

钼网被广泛用作高温催化剂载体,但关于其高温防护涂层的制备及失效机制却鲜有报道.用包埋渗硅方法在钼网表面制备了MoSi2高温抗氧化涂层,并在静态大气环境中开展了1500℃恒温氧化试验.利用X射线衍射仪(XRD)、扫描电镜(SEM)、能谱分析(EDS)等对氧化前后涂层的微观形貌和组织结构进行了表征.结果表明:1500℃氧化2h,MoSi2涂层中的Si元素会发生选择性氧化,在涂层表面形成一层连续的、具有“自愈合”功能的熔融态SiO2保护膜,阻挡氧向基体一侧的扩散,展现出了良好的高温抗氧化性能;高温条件下,涂层中的Si元素会和钼基体发生界面扩散反应生成抗氧化性能差的Mo5Si3,同时MoSi2不断地和氧发生反应生成Mo5Si3和SiO2,当涂层中的MoSi2完全转化为Mo5Si3,涂层将快速氧化失效.     

Fe/Mo多层膜的微观结构与应力研究

本文采用电子束蒸镀技术制备了Fe/Mo金属多层膜,利用TEM等手段研究了Fe与Mo层厚度对薄膜微结构应力的影响.Fe与Mo层厚度相差较大而Fe单层膜厚薄到1.2 nm时,较薄的Fe在较厚的Mo层上外延生长.随着Mo厚度的变薄,Mo/Fe厚度比减少,Mo层没有足够的自由能约束Fe原子,Fe层形成稳定的bcc结构.当Fe外延生长在Mo层上时,晶格畸变导致铁钼层间产生很大的应力,使得薄膜出现均匀的细微裂纹.用胡克定律估算了其应力范围,约104MPa数量级.     

Si片上PbTiO3薄膜的XPS研究

用溶胶 凝胶方法在Si上成功地制备了钙钛矿型的PbTiO3薄膜。X射线衍射结果显示 ,在热处理温度为 750～ 90 0℃范围内 ,随温度升高 ,薄膜由多晶结构转变为定向结晶。X射线光电子能谱分析发现 ,薄膜表面存在SiO2 薄层 ,其厚度大约为 0 6nm ,该薄层是在制膜过程中衬底Si通过PbTiO3薄膜扩散到表面与大气中的O2 反应而形成的。在 750℃热处理的薄膜 ,膜层中不含SiO2 ,但温度升高 ,膜层中存在SiO2 成分 ,这可能是Si在向表面扩散过程中与膜中的O反应生成的。表面SiO2 可通过Ar离子的轻微溅射而消除 ,而膜内SiO2 成分只能通过调节工艺参数来消除     

反应熔渗SiC/MoSi_2和SiC/Mo(Si,Al)_2复相材料抗氧化行为

研究了低成本制备技术反应熔渗方法制备的SiC/MoSi2和SiC/Mo(Si,Al)2复合材料高温氧化行为。表面氧化物的形态和氧化增重的研究结果表明,所制备复合材料高温氧化3 h后即发生钝化现象,继续在500℃再进行低温氧化试验,发现限制该材料使用的"Pest"现象消失。其中渗铝复合材料SiC/Mo(Si,Al)2高温增重较渗硅SiC/MoSi2严重。当后者中形成的SiC增强相全部为原位反应生成时,由于界面结合力提高,抗氧化能力更强。     

直流溅射工艺参数对Mo薄膜结构及电性能的影响

采用直流磁控溅射法在SLG衬底上沉积Mo薄膜,对不同溅射功率和溅射工作气压下沉积的薄膜进行X射线衍射、SEM(扫描电子显微镜)、电阻率测试,讨论了工艺参数对沉积Mo薄膜相结构、表面微观形貌、薄膜沉积速率和电学性能的影响。结果表明,随着溅射功率的增加,薄膜的结晶性能变好,沉积速率提高,在沉积功率范围内薄膜均匀致密,表面无空隙,电阻率较低;随着溅射工作气压增加,薄膜结晶性能变差,沉积速率先增加后降低,在沉积工作气压范围内,薄膜致密;随气压降低,电阻率急剧减小。因此,较高的溅射功率和较低的工作气压沉积的Mo薄膜更适合作CIGS薄膜太阳电池的BC层(背接触层)。     

XPS结合氩离子溅射剖析Si/C多层膜的化学状态

采用X射线光电子能谱结合氩离子溅射对用作锂离子电池负极的Si/C多层膜进行了表面测试及深度剖析,获得了Si/C多层膜结构中不同深度位置的成分及化学状态.分析结果表明,Si/C多层膜中各层Si、C薄膜之间存在界面元素相互扩散,扩散至相邻层薄膜中的Si、C元素主要以化合物SiC形式存在,且处于不同位置的SiC的化学键能受周...     

溅射功率对Mo掺杂ZnO(MZO)透明导电薄膜的影响

Mo原子具有较高的价态(+6),每个掺杂的Mo原子可以向ZnO晶体贡献4个自由电子,因此,Mo原子被认为是提高ZnO薄膜导电性的潜在掺杂剂.采用射频磁控溅射制备不同溅射功率下的MZO透明导电薄膜,研究溅射功率对MZ O薄膜表面形貌、微观结构、组织以及光电性能的影响.实验结果表明,不同功率制备的MZO薄膜样品都沿(002...     

氢离子束对Mo-Si多层膜界面改性的研究

为了研究氢离子束轰击Mo-Si多层膜界面的情况，采用氢离子束（能量150eV）轰击Si表面，即Si与Mo之界面。再用Kr离子束溅射刻蚀，并用俄歇电子能谱（AES）分析。实验结果说明氢离子束对Si表面轰击能有效防止界面混杂效应（intermixingeffect）。进而说明这是制备软X射线多层膜反射镜过程中解决界面混杂问题的有效途径。     

Synthesis of Mo(Si,Al)2 alloy by reactive hot pressing at low temperatures for a short time

Mo(Si,Al)2 alloy was prepared by reactive hot pressing at low temperatures for a short time under 20MPa in a vacuum using MoSi2, Mo and Al as starting powders. At 1160 °C, 5 min of soaking time was enough to obtain a high density alloy. At 1060 °C, however, 10min was needed. The formation of Mo(Si,Al)2 was accompanied by the melting of aluminum and controlled by the dissolution of molybdenum into the aluminum melt. It was proposed that the oxygen present in MoSi2 raw powder would react with aluminum and form Al2O3 in an amorphous or poor crystallization state. The mechanical properties of the alloy were a little stronger than those of monolithic MoSi2 alloy. The formed Al2O3 particles acted as crack-pinning elements, but a large toughening effect could not be obtained by this crack-pinning because of the strong interface bonding and the similar thermal expansion coefficients of Mo(Si,Al)2 and Al2O3.     

Mo base superconducting materials prepared by multi-target reactive sputtering

With an aim of developing new types of superconducting materials, Mo-N films and Mo/Si multi-layered films were fabricated by reactive and two-target sputtering methods, respectively. The superconducting properties such as Tc, Hc2and Jcwere examined. The crystal structure of Mo-N films changed from bcc to fcc with increasing N2gas flow rate during sputtering and a homogeneous fcc Mo2N superconductor was obtained. On the other hand, the superconducting characteristics of the Mo/Si multi-layered film with a layer spacing 32.3 Å were confirmed to be similar to those of amorphous Mo-Si alloys except the occurrence of anisotropic vortex pinning.     

Mo,Si混合粉末的机械合金化

利用行星式球磨机，Ｘ射线衍射仪和差热分析仪研究了Ｍｏ和Ｓｉ元素混合粉末的机械合金化行为，结果表明，随着球磨时间的延长，Ｍｏ，Ｓｉ混合粉末中首先形成Ｍｏ（Ｓｉ）超过饱和固溶体，随后相继出现Ｃ４０型ｈ－ＭｏＳｉ２和Ｃ１１ｂ型ｔ－ＭｏＳｉ２纳米晶，最终的产物是以ｈ－ＭｏＳｉ２纳米晶为主的非晶粉末混合物。     

单晶硅非平衡磁控溅射等离子体基离子注入钼的XPS研究

采用非平衡磁控溅射及射频激励产生金属等离子体，在单晶基体Si上等离子体基离子注入钼。选择不同的靶基距，即不同的Mo沉积速率，研究了沉积速率对Si中Mo注入层的影响，用X光电子能谱(XPS)对注入层中Mo的深度分布和化学态进行了分析。结果表明注入过程由两部分组成，即反冲注入(包括级联碰撞引起注入原子的位移)和金属的纯注入。随靶基距增大，沉积速率减小，样品表面沉积层厚度减小，注入层增厚。靶基距为300mm时，纯注入层厚度与理论计算值接近。XPS多道分析判断有MoSi2相生成。     

Structural and residual stress changes in Mo/a-Si multilayer thin films with annealing

The thermal and mechanical stability of molybdenum and amorphous silicon (Mo/a-Si) optical multilayers (3 and 4 nm nominal thickness of Mo and Si) at 316 °C were studied by annealing experiments. Growth of amorphous Mo-Si interlayers with a stoichiometry of 12 was observed at the Mo/a-Si interfaces. In addition, residual stresses significantly changed in the crystalline Mo and amorphous Si layers with annealing. High resolution electron microscopy, selected area electron diffraction, and X-ray diffraction of the crystalline Mo revealed that tensile stresses increased from 2 to about 10 GPa in the lateral direction (parallel to the interface plane). The compressive strains that developed in the vertical direction (perpendicular to the interface plane) are consistent with Poisson's ratio. Laser deflectometer measurements of thicker (0.1 m) amorphous silicon layers may indicate compressive-stress relaxation in the amorphous silicon with annealing, consistent with other investigations. Overall, the residual stress in a 40-bilayer film changes from about –0.5 to about +1.5 GPa. Structural transformation after relatively short annealing times at the interfaces in the thin amorphous Mo-Si interlayers may rationalize increased tensile strains in the Mo layers.     

Nano-size crystallites in Mo/Si multilayer optics

In this paper, we present an experimental study on the structural and crystalline properties of electron beam evaporated Mo/Si multilayers. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) experiments were used to characterize the crystalline nature of Mo and Si. TEM and XRD show that Si grows amorphous, while Mo clearly crystallizes. The Mo crystallites show no preferred growth orientations and a columnar growth mode, with crystallite sizes limited by the Mo layer thickness. From samples with low Mo content, we show that crystallization of Mo starts directly at the Mo/Si interfaces, with the formation of a Mo₃Si compound. The crystallite lattice strains that develop during Mo-on-Si growth due to lattice mismatches, will add to the macroscopic multilayer stress. By comparing Mo lattice strains derived from XRD with changes in substrate curvatures, as determined by interferometry, we show that compressive and tensile substrate deformations are predominantly caused by the internal crystallite strains.     

Determination of crystallization as a function of Mo layer thickness in Mo/Si multilayers

Mo/Si multilayer samples with different Mo layer thickness were deposited by electron beam evaporation, while Kr⁺ ions (300 eV) were used for polishing the Si layers. Crystallization as a function of the Mo layer thickness deposited was investigated by grazing incidence X-ray diffraction, giving information on the crystalline phases, average size and crystallite formation. Comparison of these parameters for the samples examined provided novel results, especially regarding the in-plane and in-depth average sizes of the crystallites. The most important result is that crystallization takes place already when a 1 nm thick Mo layer has been deposited. Moreover, the average in-plane size of the crystallites was found to be independent of the layer thickness, while the average in-depth size corresponded to the thickness of the Mo layer. Depositions consist of polished Si layers were found to give a larger amount of crystalline material compared to those consist of unpolished Si layers.     

Nb-Si基合金表面Mo-Si-B涂层制备及抗氧化性能

为提高Nb-Si合金的抗高温氧化性能,在其表面制备Mo-Si-B涂层。通过Thermo-Calc计算的方法,从热力学角度分析NaF和AlF_3两种激活剂对Si-B二元共渗的影响。结果表明:以NaF为激活剂时可以实现Si-B的二元共渗,而以AlF3为激活剂时,难以实现Si-B的二元共渗。通过爆炸喷涂结合包埋渗的方法在Nb-Si合金表面成功制备Mo-Si-B涂层,涂层主要由有弥散硼化物分布的MoSi2外层和未反应的Mo内层构成。涂层在1250℃氧化100h后涂层的氧化增重仅为1.52mg/cm~2,良好的抗高温氧化性能是由于涂层在高温氧化过程中形成了一层具有保护性的硼硅酸盐层。     

保护气氛下反应烧结MoSi_2/Al_2O_3复合陶瓷

以金属Mo粉、Si粉和Al粉为原料,采用反应烧结法制备MoSi_2/Al_2O_3陶瓷复合材料,有效增强其室温韧性和强度,并揭示其电阻率随烧结温度变化规律。利用XRD和SEM分析不同温度烧结后MoSi_2/Al_2O_3复合材料试样的物相组成和微观结构;研究不同烧结温度下试样的力学和电学性能。结果表明:在氩气保护气氛下1 200℃时,MoSi_2/Al_2O_3陶瓷复合材料的各项性能较好,其显气孔率为20.7%,体积密度为4.8g/cm~3,断裂韧性值为9.72MPa·m1/2,电阻率为6.0×10~(-2)Ω·cm。所制备的MoSi_2/Al_2O_3陶瓷复合材料物相结构主要由Al_2O_3包覆MoSi_2形成的连续包覆相组成,组织结构均匀。烧结温度为1 200℃时,MoSi2导电相由弥散分布变成相互连接的网络状分布,且Al_2O_3包覆MoSi_2导电相的包覆层变薄,包裹的MoSi_2颗粒之间易于突破包覆相而互相连通,有助于降低电阻率。