沉积功率和退火工艺对PE-ALD氧化铝薄膜的影响

Al2O3薄膜常用于有机电子器件的稳定化封装.除了薄膜的水气渗透率特性,薄膜的表面粗糙度、润湿性和折射率等性能也会影响薄膜的最终封装效果.采用自制等离子增强原子层沉积(PE-ALD)系统在低温下成功制备了Al2O3薄膜,研究了沉积功率和退火参数对Al2O3薄膜微观形貌和性能的影响.结果表明,Al2O3薄膜的生长速率和折射率随沉积功率的增加分别呈现先增加后下降和不断增加的趋势,当沉积功率为1 800 W时,薄膜的线性生长速率达到0.27 nm/cycle,远高于传统热原子层沉积技术的沉积速率.退火处理不会改变Al2O3薄膜晶态,但改善了薄膜的表面粗糙度,降低了接触角和有机基团红外强度.得到了最佳的PE-ALD薄膜制备工艺条件,实现了对有机发光二极管器件的有效封装.     

激光熔化沉积参数对316L单道几何特征的影响

激光熔化沉积(lasermelting deposition,LMD)是一种先进的金属增材制造技术,具有成形速度快、无模具制造、多轴操作系统和多余粉末可有效回收等特点。但是沉积过程中会出现成形质量不良的现象,导致LMD零件致密度下降,疲劳性能降低。为了提高316L奥氏体不锈钢LMD零件的致密度与疲劳力学性能,针对LMD单道沉积工艺过程,开展实验研究分析不同工艺参数下对单道沉积几何特征的影响。本文使用316L奥氏体不锈钢粉末在激光熔化沉积设备上进行相应的工艺研究,探索了激光功率与扫描速度对单道沉积几何特征的影响。通过对工艺参数与各几何特征进行回归分析,建立了回归模型,并确立了工艺参数对几何特征的影响规律。该工作为后续316L激光熔化沉积零件疲劳实验试样的制备提供基础与参数指导。     

反应压力对MOCVD法沉积ZnO薄膜性质的影响

研究了反应压力对金属有机化学气相沉积(MOCVD)技术制备未掺杂ZnO薄膜的微观结构和光电特性影响.X射线衍射(XRD)和扫描电子镜(SEM)的研究结果表明,随着反应压力的降低,ZnO薄膜(002)择优峰的强度呈现相对减弱趋势,并且出现了较强的(110)峰;Hall测量表明,低的反应压力有助于提高薄膜电学特性.200 Pa时制备出的ZnO薄膜具有明显的"类金字塔"状绒面结构,电阻率为1.28×10-2 Ω·cm.实验中沉积的ZnO薄膜在600～2 600 nm内平均透过率超过80%,而短波长范围由于光散射作用,ZnO薄膜的垂直透过率有所下降.     

CdS薄膜的制备及其性能

采用化学池沉积(CBD)法,在三种衬底(玻片、ITO玻片、SnO2玻片)上沉积CdS薄膜,并利用扫描电镜(SEM)、透射光谱、X射线衍射(XRD)和微电流高阻计等方法对沉积膜进行了测试分析,计算出CdS薄膜的能隙宽度和电导激活能,阐述了CBD法中CdS薄膜的生长沉积机制以及不同衬底对沉积效果的影响.结果表明:不同衬底的成膜效果差异较大,其中以SnO2玻片效果最佳.     

离子束增强沉积氮化硅薄膜生长及其性能研究

用离子束增强沉积技术合成了氮化硅薄膜并研究了薄膜的组分、性能和结构.结果表明,离子束增强沉积生长的氮化硅薄膜的组分比,可借助于调节氮离子和硅原子到达率之比加以控制.在合适条件下生长的氮化硅薄膜,其红外吸收特征峰在波数为840cm~(-1)附近,光折射率在2.2到2.6之间,其组分为Si_3N_4用RBS、AES、TEM、SEM、ED及扩展电阻,测量和观察生成的氮化硅薄膜的组分深度分布及结构.发现,离子束增强沉积制备的氮化硅薄膜,存在着表面富硅层、氮化硅沉积层及混合过渡层这样的多层结构.薄膜呈球状或方块状堆积.基本上是无定形相,但局部可观察到单晶相的存在.离子束增强沉积制备的氮化硅薄膜中的含氧量比不用离子束辅助沉积的显著减少.     

CdS薄膜的制备及其性能

采用化学池沉积(CBD)法,在三种衬底(玻片、ITO玻片、SnO2 玻片)上沉积CdS薄膜,并利用扫描电镜(SEM)、透射光谱、X射线衍射(XRD)和微电流高阻计等方法对沉积膜进行了测试分析,计算出CdS薄膜的能隙宽度和电导激活能,阐述了CBD法中CdS薄膜的生长沉积机制以及不同衬底对沉积效果的影响.结果表明:不同衬底的成膜效果差异较大,其中以SnO2 玻片效果最佳     

DB-FIB中由不完全分解的Pt导致样品表面污染的解决方法

双束聚焦离子束（DB-FIB）已经成为半导体工业中,尤其是失效分析（FA）工作中非常重要的工具,被广泛应用于集成电路的缺陷分析和修整、TEM（透射电子显微镜）的薄片试样制备等方面。在制备TEM样品时,为了避免后期切削时Ga离子束对表层的损伤,在Ga离子束切削样品之前往往会在样品需要观测的位置上沉积一层Pt薄膜作保护层。目前,最常用的方法是先用电子束辅助沉积（E-beam assisted deposition）的方法在样品表面镀一层Pt薄膜,然后再在其上用离子束辅助沉积（I-beam assisted deposition）的方法镀一层较厚的Pt保护层。但是最近在TEM样品观测过程中,发现用DB-FIB制备的样品表面会出现球状或岛状的黑色颗粒,这种现象严重影响TEM对样品的分析。经EDX成分分析,该颗粒的主要成分为Pt,C,Ga.。通过设计一系列的实验对黑色颗粒形成原因及解决方法进行了研究。实验结果表明,这些颗粒的出现与I-BeamPt的沉积电流有关,采用48pA的I-Beam电流沉积Pt会避免黑色颗粒的出现,并且对该模型作出了解释。     

联氨对化学水浴沉积ZnS薄膜的影响

在A(ZnSO4、SC(NH2)2、NH4OH)和含有联氨的B(ZnSO4、SC(NH2)2、NH4OH、(NH2)2)两种水溶液中采用化学水浴法沉积ZnS薄膜,研究了联氨对薄膜沉积过程和薄膜性质的影响.结果表明,加入少量联氨以后,薄膜沉积速度明显增加.两种溶液沉积的ZnS都为立方相结构,且含有联氨的B溶液沉积的ZnS薄膜表面附着颗粒较少.在含有联氨的B溶液中沉积的ZnS薄膜结晶度和短波区的透过率均高于A溶液沉积的ZnS薄膜.将两种溶液沉积的ZnS薄膜作为电池缓冲层制备铜铟镓硒(CIGS)薄膜太阳电池,加入联氨沉积的ZnS制备的CIGS电池转换效率达到7.77%,比不加联氨沉积的ZnS制备的CIGS电池转换效率提高了1.3%.     

沉积条件对氢化锂薄膜形貌和沉积速率的影响

为了研究沉积条件对氢化锂薄膜沉积速率和表面形貌的影响,采用脉冲激光沉积方法在Si(100)基片上沉积了氢化锂薄膜.通过改变靶基距和氢压等手段来控制薄膜的沉积速率,得到了氢压与沉积速率和薄膜表面质量的关系.结果表明,随着氢压和靶基距的增加,氢化锂薄膜的沉积速率逐渐下降;适当增加氢压可以降低氢化锂薄膜的表面粗糙度.从薄膜生...     

变温LPCVD沉积氮化硅薄膜的均匀性优化

以低压化学气相沉积(LPCVD)热壁立式炉为实验平台,由二氯硅烷和氨通过LPCVD工艺合成氮化硅薄膜,利用降温成膜提高氮化硅薄膜的膜厚均匀度.基于气体碰撞理论建立了氮化硅薄膜沉积速率与反应气体浓度的关系式.分析比较了LPCVD炉内不同升温速率沉积氮化硅薄膜的表面性能.发现在变温沉积阶段,选择合适的降温速率是实现薄膜沉积...     

Micro‐/Nanostructured Highly Crystalline Organic Semiconductor Films for Surface‐Enhanced Raman Spectroscopy Applications

The utilization of inorganic semiconductors for surface‐enhanced Raman spectroscopy (SERS) has attracted enormous interest. However, despite the technological relevance of organic semiconductors for enabling inexpensive, large‐area, and flexible devices via solution processing techniques, these π‐conjugated systems have never been investigated for SERS applications. Here for the first time, a simple and versatile approach is demonstrated for the fabrication of novel SERS platforms based on micro‐/nanostructured 2,7‐dioctyl[1]benzothieno[3,2‐b][1]benzothiophene (C8‐BTBT) thin films via an oblique‐angle vapor deposition. The morphology of C8‐BTBT thin films is manipulated by varying the deposition angle, thus achieving highly favorable 3D vertically aligned ribbon‐like micro‐/nanostructures for a 90° deposition angle. By combining C8‐BTBT semiconductor films with a nanoscopic thin Au layer, remarkable SERS responses are achieved in terms of enhancement (≈10⁸), stability (>90 d), and reproducibility (RSD < 0.14), indicating the great promise of Au/C8‐BTBT films as SERS platforms. Our results demonstrate the first example of an organic semiconductor‐based SERS platform with excellent detection characteristics, indicating that π‐conjugated organic semiconductors have a great potential for SERS applications.     

树枝状Ag基底的制备及其SERS活性研究

研究了一种表面增强拉曼散射(SERS)活性Ag基底的制备新方法。通过电化学方法和液相生长方法相结合在金属Al表面制备SERS活性Ag膜。用扫描电子显微镜(SEM)表征Ag膜的表面形貌,以结晶紫(C25 H30N3Cl·H2O)为拉曼探针分子,研究了基底的SERS增强效果。研究表明:结晶紫分子吸附在Ag膜表面的SERS强度随电沉积时间的增加呈现先增强后减弱的趋势;进一步的Ag增强剂和引发剂的混合溶液对电沉积Ag膜的浸泡处理可以调节基底Ag膜的结构形态,增强电沉积基底Ag膜的SERS活性。     

Intergrowth mechanism of silicon nanowires and silver dendrites

The intergrowth mechanism of silicon nanowires and silver dendrites formed by electroless metal deposition has been investigated by scanning electron microscopy. A self-assembled localized microscopic electrochemical cell model can adequately describe the self-organized Si nanowires growth. Using these in situ prepared Si nanowire arrays as templates, a diffusion-limited aggregation process is proposed to explain the formation of the silver dendritic nanostructures.     

在硅片上电沉积不同形貌的ZnO纳米结构的研究

采用简单的电化学沉积方法,通过调节电解液浓度和pH值,在硅衬底上实现了ZnO纳米结构的形貌控制。通过X射线衍射、扫描电镜和光致发光谱等表征手段对不同形貌的ZnO纳米结构进行了研究。研究发现,通过调节沉积条件,可以获得纳米棒、纳米簇丛和纳米片等不同形貌的ZnO纳米结构。其中,溶液pH值是纳米ZnO从一维结构到二维结构转变的关键因素。当pH值为12时,所获得的纳米ZnO为二维片状结构。光致发光谱显示二维ZnO纳米片的紫外本征峰相对于一维ZnO纳米棒发生了明显的蓝移,并且可见区的发光峰大大降低。这一结构将在光电器件、传感器等领域有很好的应用前景。     

Integrated Microdroplets Array for Intelligent Electrochemical Fabrication

The efficiency and accuracy of material fabrication are closely related to the quantity and quality of material structures/properties, which usually involves multiple parameters with high cost and time waste. Here, an intelligent and high‐throughput platform is developed to regulate multiple electrodeposition parameters of a microdroplets array for controlling and predicting nanostructures. On such platform, the minipillars can anchor the microdroplets as individual deposition reactors, and the electrodes are integrated on one side to achieve high‐throughput and simultaneous electrochemical fabrication. Such integrated and intelligent platform has been employed to investigate gold nanostructures via regulating the deposition parameters (time, potential, HAuCl₄ concentration, Cl^?/SO₄^2? concentration in electrolyte, temperature, and humidity), and to establish the database of electrochemically‐fabricated gold nanostructures for guiding the design and fabrication of specific gold nanostructures. It is believed that such platform can act as a pioneer to promote the development of materials science by coupling intelligence technology with nanomaterial fabrication.     

Near-Infrared II Plasmonic Au@Au–Ag Dot-in-Cubic Nanoframes for In Vivo Surface-Enhanced Raman Spectroscopic Detection and Photoacoustic Imaging

Near-infrared II (NIR-II) plasmonic noble-metallic nanostructures are highly desirable for in vivo photodiagnostics because of their multiple functionalities and deep-tissue optical imaging capability. Herein, a novel class of Au@Au–Ag dot-in-cubic nanoframes (DCFs) comprising a solid Au core and a Au–Ag alloy shell with a wall hole on each side face is reported, which exhibit remarkable plasmonic properties spectrally tunable beyond 1400 nm while maintaining a small size. The synthesis of Au@Au–Ag DCFs is principally based on the facet-selective etching of Ag atoms and co-deposition of Au and Ag atoms on the edges and corners of Au@Ag dot-in-cubes. The geometry (e.g., edge length and wall hole size) can be controllably tailored by simply varying the silver nitrate and chloroauric acid concentrations. Superior in vitro and in vivo NIR-II photoacoustic imaging performances of Au@Au–Ag DCFs are demonstrated. Additionally, remarkable NIR-II surface-enhanced Raman spectroscopy (SERS) activity of Au@Au–Ag DCFs is evidenced with the maximum NIR-II SERS enhancement occurring at a plasmon resonance wavelength blue-shifting from the incident laser wavelength and an excellent effective detection depth. Finally, the potential of the developed Au@Au–Ag DCFs is highlighted for in vivo NIR-II SERS detection of microtumors in animals.     

纳米结构分子吸附引起的表面增强拉曼散射研究

利用模板印刷技术,制备了具有不同局域表面等离子体共振(LSPR)峰的Au纳米空心半球壳结构,并以4-巯基苯胺(4-ATP)为探针分子研究了纳米结构表面吸附分子对表面增强拉曼散射(SERS)强度的影响。结果表明,当纳米结构的LSPR峰位处于激发光波长的短波长或"马鞍型"位置时,SERS强度随吸附分子数的增加而增大;当处于长波长位置时,SERS强度呈现先增大后减小的趋势。利用分子吸附理论和纳米结构表面局域场强度变化,对此现象进行了解释。     

Graphene as an Electron Shuttle for Silver Deoxidation: Removing a Key Barrier to Plasmonics and Metamaterials for SERS in the Visible

The role of graphene in enabling deoxidation of silver nanostructures, thereby contributing to enhance plasmonic properties and to improve the temporal stability of graphene/silver hybrids for both general plasmonic and meta‐materials applications, as well as for surface enhanced Raman scattering (SERS) substrates, is demonstrated. The chemical mechanism occurring at the graphene–silver oxide interface is based on the reduction of silver oxide triggered by graphene that acts as a shuttle of electrons and as a kind of catalyst in the deoxidation. A mechanism is formulated, combining elements of electron transfer, role of defects in graphene, and electrochemical potentials of graphene, silver, and oxygen. Therefore, the formulated model represents a step forward from the simple view of graphene as barrier to oxygen diffusion proposed so far in literature. Single layer graphene grown by chemical vapor deposition is transferred onto silver thin films, a periodic silver fishnet structure fabricated by nanoimprint lithography, and onto silver nanoparticle ensembles supporting a localized surface plasmon resonance in the visible range. Through the study of these nanostructured graphene/Ag hybrids, the effectiveness of graphene in preventing and reducing oxidation of silver plasmonic structures, keeping silver in a metallic state over months at air exposure, is demonstrated. The enhanced and stable plasmonic properties of the silver‐fishnet/graphene hybrids are evaluated through their SERS response for detecting benzyl mercaptane.     

Near‐Field Enhanced Plasmonic‐Magnetic Bifunctional Nanotubes for Single Cell Bioanalysis

Near‐field enhanced bifunctional plasmonic‐magnetic (PM) nanostructures consisting of silica nanotubes with embedded solid nanomagnets and uniformly dual‐surface‐coated plasmonic Ag nanoparticles (NPs) are rationally synthesized. The solid embedded sections of nanotubes provide single‐molecule sensitivity with an enhancement factor up to 7.2 × 10⁹ for surface‐enhanced Raman scattering (SERS). More than 2× SERS enhancement is observed from the hollow section compared to the solid section of the same nanotube. The substantial SERS enhancement on the hollow section is attributed to the dual‐sided coating of Ag NPs as well as the near‐field optical coupling of Ag NPs across the nanotube walls. Experimentation and modeling are carried out to understand the dependence of SERS enhancement on the NP sizes, junctions, and the near field effects. By tuning the aspect ratio of the embedded nanomagnets, the magnetic anisotropy of nanotubes can be readily controlled to be parallel or vertical to the long directions for nano‐manipulation. Leveraging the bifunctionality, a nanotube is magnetically maneuvered to a single living mammalian cell amidst many and its membrane composition is analyzed via SERS spectroscopy.     

Etching‐Free Epitaxial Growth of Gold on Silver Nanostructures for High Chemical Stability and Plasmonic Activity

A robust method for epitaxial deposition of Au onto the surface of Ag nanostructures is demonstrated, which allows effective conversion of Ag nano­structures of various morphologies into Ag@Au counterparts, with the anisotropic ones showing excellent plasmonic properties comparable to the original Ag nanostructures while significantly enhanced stability. Sulfite plays a determining role in the success of this epitaxial deposition as it strongly complexes with gold cations to completely prevent galvanic replacement while it also remains benign to the Ag surface to avoid any ligand‐assisted oxidative etching. By using Ag nanoplates as an example, it is shown that the corresponding Ag@Au nanoplates possess remarkable plasmonic properties that are virtually Ag‐like, in clear contrast to Ag@Au nanospheres that exhibit much lower plasmonic activities than their Ag counterparts. As a result, they display high durability and activities in surface‐enhanced Raman scattering applications. This strategy may represent a general platform for depositing a noble metal on less stable metal nanostructures, thus opening up new opportunities in rational design of functional metal nanomaterials for a broad range of applications.