C60—聚苯乙烯LB膜摩擦学性能的初步研究

介绍了Ｃ６０－聚苯乙烯（Ｃ６０－Ｐｓｔ）ＬＢ膜的部分研究结果：合成方法、ＬＢ膜制备、用原子力／摩擦力显微镜测试的Ｃ６０－聚苯乙烯ＬＢ膜的表面微观形貌及轻载荷下的摩擦力等微观摩擦学性能。     

Synthesis of Mn doped ZnO nanocrystals by solvothermal route and its characterization

Undoped and Manganese doped Zinc Oxide were prepared by solvothermal technique. The structural analysis was carried out using X-ray diffraction. It showed that the undoped Zinc Oxide and Manganese doped Zinc Oxide nanocrystals to exhibit hexagonal wurtzite structure. Grain sizes were estimated from Atomic Force Microscopy and Transmission Electron Microscopy images. The surface morphological studies from Scanning Electron Microscope, Transmission Electron Microscope and Atomic Force Microscope depicted spherical particles with formation of clusters. The magnetic behavior studied by Vibrating Sample Magnetometer indicated paramagnetic behaviour. Hyperfine splitting is observed using Electron Spin Resonance studies.     

原子力显微镜在材料研究中的应用

简述原子力显微镜的工作原理及特点,以实例介绍其在材料研究中的应用,指出原子力显微镜在材料的研究过程中有广阔的应用前景。     

Micro 3D measurement method using SEM

Three diamensional (3D) measurement method by Scanning Electron Microscope (SEM) has already been proposed by using the principle of shadow moiré. In the method, the image of original grid in shadow moiré image must be clearly removed in fringe analysis process in order to perform high resolution analysis. A new method based on the principle of projection moiré is proposed to solve the trouble concerning the grid. In this paper, the mechanism of producing some shadows of grid on the surface of the object by back scattering electron beam in the new method is discussed. Fringe image as shadow of grid is analyzed by Wavelet transform. The precise 3D measurement is realized by using the phenomenon of shadows of grid. Furthermore, a 3D micro structure on the head of a hard disk is measured. From the comparison of results obtained by Atomic Force Microscope (AFM), it is confirmed that the proposed method has high-resolution power(about 20nm).     

Nanoscale leakage current measurements in metal organic chemical vapor deposition crystalline SrTiO3 films

The properties of SrTiO₃ thin films, grown by liquid injection metal organic chemical vapor deposition on Si/SiO₂, using a mixture of precursors, have been investigated at the nanoscale using an Atomic Force Microscope in the so-called Conductive Atomic Force Microscopy mode. Maps of the leakage currents with a nanometric resolution have been obtained on films elaborated at different temperatures and stoichiometries in order to discriminate the role of each parameter on the onset of leakage currents in the resulting layers. It appears that the higher the deposition temperature, the higher the leakage currents of the films. The mapping with a nanometric precision allows to show a heterogeneous behaviour of the surface with leaky grains and insulating boundaries. The study of films elaborated at the same temperature with different compositions supports the assumption that the leakage currents on Ti-rich layers are far higher than on Sr-rich layers.     

Localized oxidation influence from conductive atomic force microscope measurement on nano-scale I-V characterization of silicon thin film solar cells

Nano-scale current-voltage (I-V) characteristics of hydrogenated microcrystalline silicon (μc-Si:H) prepared by Hot-Wire CVD (HWCVD) technique have been studied by Conductive Atomic Force Microscope (Conductive-AFM) under atmospheric conditions. It is demonstrated that a local modification is caused by the current, detected as a dramatic decrease in the forward biased current of I-V characteristics with the number of repeated scans. On the other hand, smaller change of reverse biased current is observed after the repeated scans. On the base of these results, we discuss and demonstrate the validity of our proposed new junction characterization method at the nanometer scale; that is, simultaneous nano-scale Topographical and Current-Voltage Imaging (TCVI) for Silicon (Si) thin film solar cells.     

Chemomechanical nanolithography: nanografting on silicon and factors impacting linewidth

We present a two-fold extension of previous work on Atomic Force Microscope-based chemomechanical functionalization: (1) chemomechanical nanografting, which extends chemomechanical functionalization to a more stable initial surface, and (2) linewidth studies that show the impact of force and Atomic Force Microscope probe tip wear on patterning resolution. Alkene, alcohol, and alkyl halide molecules were nanografted to silicon and imaged with in situ atomic force microscopy, time-of-flight secondary ion mass spectrometry with Automated eXpert Spectrum Image Analysis, and scanning electron microscopy. Chemomechanical nanografting demonstrated linewidths down to 50 nm. Lines written on hydrogen-terminated silicon were used to explore the impact of tip radius and tip wear on linewidth when using Si3N4 coated tips.     

Probing nanomechanical properties of nickel coated bacteria by nanoindentation

As a powerful method for the study of mechanical properties at micro-/nanoscale, nanoindentation was applied to measure the hardness and elastic modulus of bacteria-templated metallic nanomaterials for the first time. Based on the morphological characterization by Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM), nanoindentation testing results showed that after coating with nickel via electroless chemical plating, the elastic modulus and hardness of bacterial cells were increased about 17 times and 50 times, respectively, indicating a great improvement in mechanical properties. This study would lay a forceful mechanical foundation for a better and general understanding of this kind of biotemplated metallic nanomaterials, which showed potential applications in nanoelectronics, nanomagnetism and nanomechanics.     

Hydrogen-bonding layer protecting polyelectrolyte capsules and its mechanical property study with atomic force microscope

The hydrogen-bonding multilayered polyelectrolyte capsules with sizes around 6 microm were fabricated by layer-by-layer self-assembly method. The morphology of the obtained capsules was observed with Scanning Electron Microscope (SEM), Confocal Laser Scanning Microscope (CLSM) and Atomic Force Microscope (AFM), respectively. The elastic properties of the capsules were studied with AFM. The capsule was pressed by cantilever with different lengths, a glass bead glued at the end of the cantilever. The force curves were measured on the capsule in air. The Young's modulus of the capsule was obtained (E = 170 MPa for the loading). Results show that this model can predict the elastic deformation of the microcapsule. The accuracy of the elastic deformation of polymer capsule can be ensured using a cantilever of mediate stiffness. Our results show that the existence of the hydrogen-bonding layer makes the multilayered polyelectrolyte harder in comparison with the pure multilayered polyelectrolyte capsules.     

On the correlation between morphology and electronic properties of copper phthalocyanine (CuPc) thin films

The morphology of vacuum deposited copper phthalocyanine (CuPc) thin films surface deposited on Si(111) have been studied using the contact mode Atomic Force Microscope (AFM). The influence of substrate temperature during deposition and of the post-deposition UHV annealing on surface roughness as well as on the average and maximum grain height was determined. The observed changes of surface morphology were in a good correlation with the shift of surface Fermi level position in the band gap after O₂ exposure determined in our recent photoemission studies.     

Interfacial energy between carbon nanotubes and polymers measured from nanoscale peel tests in the atomic force microscope

The future development of polymer composite materials with nanotubes or nanoscale fibers requires the ability to understand and improve the interfacial bonding at the nanotube–polymer matrix interface. In recent work [Strus MC, Zalamea L, Raman A, Pipes RB, Nguyen CV, Stach EA. Peeling force spectroscopy: exposing the adhesive nanomechanics of one-dimensional nanostructures. Nano Lett 2008;8(2):544–50], it has been shown that a new mode in the Atomic Force Microscope (AFM), peeling force spectroscopy, can be used to understand the adhesive mechanics of carbon nanotubes peeled from a surface. In the present work, we demonstrate how AFM peeling force spectroscopy can be used to distinguish between elastic and interfacial components during a nanoscale peel test, thus enabling the direct measurement of interfacial energy between an individual nanotube or nanofiber and a given material surface. The proposed method provides a convenient experimental framework to quickly screen different combinations of polymers and functionalized nanotubes for optimal interfacial strength.     

Measuring Energies at the Nanometer-Scale of Molecular Organic Materials with an Atomic Force Microscope: TTF-TCNQ as a Case Study

The elastic response of molecular organic materials to external mechanical nanoindentations in the nano- and low micronewton force range can be characterized using ultrasharp cantilever tips of an Atomic Force Microscope (AFM). Because clear distinction between elastic and plastic deformation is achieved, the maximal accumulated elastic energy can be directly determined from the force vs. penetration curves, giving an estimate of the characteristic energies of the materials.     

Properties of interfacial transition zones in recycled aggregate concrete tested by nanoindentation

The properties of new Interfacial Transition Zone (ITZ) and old ITZ in Recycled Aggregate Concrete (RAC) were investigated by Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and nanoindentation. From the SEM images, obvious voids and high concentration of calcium hydroxide can be found in both old ITZ and new ITZ in RAC. Based on the nanoindentation study, it is indicated that the thicknesses of old and new ITZs are in the range 40–50 μm and in the range 55–65 μm, respectively. It is also found that the average indentation modulus of old ITZ is 70–80% of that of old paste matrix, while the average indentation modulus of new ITZ is 80–90% of that of new paste matrix. Additionally, the influences of mix proportion, aggregate types and hydration age on the properties of ITZs in RAC are discussed in this study.     

溶胶-凝胶法与射频磁控溅射法制备ZnO薄膜及其表征对比

分别对溶胶-凝胶法和磁控溅射法制备ZnO进行了详细的介绍,并借助X射线衍射、原子力显微镜、拉曼光谱分析、紫外吸收等检测手段对这两种方法生长的薄膜进行了分析比较.分析显示:相同石英基底,相同退火温度下生长ZnO薄膜,磁控溅射法生长的ZnO薄膜要比溶胶-凝胶法生长的ZnO薄膜有更优异的c轴取向特性,生长的薄膜结晶更加均匀、致密.     

AFM and SEM observation on mechanism of fatigue crack growth in an Fe-Si single crystal

Fatigue crack growth tests are carried out on sheets of an Fe-3.2% Si single crystal with a crystallographic orientation appropriate for striation formation. The behaviour of slip near a crack tip during the loading and unloading parts of a fatigue cycle is observed using an Atomic Force Microscope and a Scanning Electron Microscope. The fracture surfaces are also analysed with an AFM and an SEM. The mechanism of fatigue crack growth is discussed based on the observations, and a fundamental kinematic model for fatigue crack growth is proposed. The model gives a reasonable explanation for both the crack growth and striation formation.     

AFM常见针尖与试样面间力的计量研究

首先建立了原子力显微镜（AFM）针尖与试样面力学计量的物理模型，介绍了研究该问题的方法。根据Hamaker理论，利用微观连续介质法建立了AFM常见的圆锥型、四棱锥型和抛物面型针尖与试样面间的包含斥力的力学模型。经计算得到仿真结果，仿真结果与实验结果一致。     

RM 8111: Development of a Prototype Linewidth Standard

Staffs of the Semiconductor Electronics Division, the Information Technology Laboratory, and the Precision Engineering Laboratory at NIST, have developed a new generation of prototype Single-Crystal CD (Critical Dimension) Reference (SCCDRM) Materials with the designation RM 8111. Their intended use is calibrating metrology instruments that are used in semiconductor manufacturing. Each reference material is configured as a 10 mm × 11 mm silicon test-structure chip that is mounted in a 200 mm silicon carrier wafer. The fabrication of both the chip and the carrier wafer uses the type of lattice-plane-selective etching that is commonly employed in the fabrication of micro electro-mechanical systems devices. The certified CDs of the reference features are determined from Atomic Force Microscope (AFM) measurements that are referenced to high-resolution transmission-electron microscopy images that reveal the cross-section counts of lattice planes having a pitch whose value is traceable to the SI meter.     

A facile way to optimize thermoelectric properties of SnSe thin films via sonication-assisted liquid-phase exfoliation

In our work, SnSe nanosheets and nanostructured thin films were successfully synthesized via sonication-assisted exfoliation and coating process. The SnSe nanosheets respond to a uniform lateral size, with two to three single layers by 2.82 nm and 280 nm² of average thickness and average area, respectively. The results were confirmed by Scanning Electron Microscope, Transmission Electron Microscope, and Atomic Force Microscope. X-ray diffraction and Raman spectra indicate that the SnSe nanosheets have high crystalline quality along a-axis. The SnSe nanostructured thin films were prepared in various thicknesses from 350 to 650 nm. The highest power factor value is achieved at 450 nm in 375–600 K temperature range. A simple method of fabrication and controllable thermoelectric properties of SnSe nanostructured thin films as well as other two-dimensional (2D) materials are introduced.

     

Effect of sliding velocity on capillary condensation and friction force in a nanoscopic contact

The influence of sliding velocity on the friction force in a nanoscopic contact was studied on a hydrophilic silicon nitride surface with an Atomic Force Microscope. By submitting a nanoscopic contact to small oscillating lateral displacements, we observe both decreases of the friction force and of the contact radius with an increase of the sliding velocity. We found experimentally that this decrease of the friction force and of the contact radius is correlated to a decrease of the capillary force.     

Co／Cu／Co三明治膜的巨磁电阻效应研究

采用超高真空电子束蒸发方法在硅单晶衬底上制备了Ｃｏ／Ｃｕ／Ｃｏ三明治膜,研究了衬底晶向、过渡工层材料和生长室温度对三明治膜中巨磁电阻效应的影响;结合原子力显微镜表面形貌观察,探讨了三明治膜表面（界面）组糙度与其巨磁电阻效应的内在关系;还分析了三明治膜经高温热退火后巨磁电阻效应退化的物理机制。