扫描隧道显微镜纳米云纹法的实验研究

提出了应用扫描隧道显微镜(STM)纳米云纹法测量面内位移的原理。测量中,把扫描隧道显微镜的探针扫描线作为参考栅,把物质原子晶格栅结构作为试件栅,对这两组栅线干涉形成的云纹进行了纳米级变形测量。对扫描隧道显微镜纳米云纹的形成原理及测量方法进行了详尽的讨论,并运用该方法对高定向裂解石墨(HOPG)的纳米级变形虚应变进行了测量研究,得到了随扫描范围变化的虚应变场,并与理论值进行了比较。     

扫描探针显微学中的云纹方法

在扫描探针显微镜（SPM）的扫描过程中，由SPM的扫描线与物质表面周期性晶格结构进行干 涉可以形成纳米云纹图像.采用高取向热解石墨（HOPG）和云母作为试件，分别对扫描隧道 显微镜（STM）和原子力显微镜（AFM）云纹进行了研究，实验结果与理论分析完全一致.SPM 纳米云纹法在纳米测量和表征方面具有较大的应用前景. 关键词： 云纹 SPM 晶格栅线 纳米测量     

X射线干涉仪实现扫描探针显微镜样板线间距纳米测量

X射线干涉仪以非常稳定的单晶硅晶格作为长度单位 ,可以实现亚纳米精度的微位移测量。提出了将 X射线干涉仪和扫描隧道显微镜结合起来 ,利用单晶硅的晶格尺度测量扫描探针显微镜样板节距的技术方案 ,并进行了实验研究     

X射线干涉仪实现扫描控针显微镜样板线间距纳米测量

X射线干涉仪以非常稳定的单晶硅晶格作为长度单位,可以实现亚纳米精度的微位移测量。提出了将X射线干涉仪和扫描隧道显微镜结合起来,利用单晶硅的晶格尺度测量扫描探针显微镜样板节距的技术方案,并进行了实验研究。     

AFM制作纳米光栅技术研究

在扫描探针纳米加工技术的基础上,提出了利用原子力显微镜(AFM)来制作高频光栅的新工艺。利用AFM硅制探针,在接触模式下对光盘(聚碳酸酯材料)进行刻划试验。对刻划光栅的工艺参数进行优化,得到了纳米量级光栅。并将刻划所得光栅应用于数字云纹法,与数字参考栅干涉形成微/纳米数字云纹。实验结果表明,该法所制得的光栅可以应用于实际变形的测量。     

qPlus型原子力显微镜技术

扫描探针显微镜主要包括扫描隧道显微镜和原子力显微镜,其利用尖锐的针尖逐点扫描样品,可在原子和分子尺度上获取表面的形貌和丰富的物性,改变了人们对物质的研究范式和基础认知。近年来,qPlus型高品质因子力传感器的出现将扫描探针显微镜的分辨率和灵敏度推向了一个新的水平,为化学结构、电荷态、电子态、自旋态等多自由度的精密探测和操控提供了前所未有的机会。文章首先简要介绍原子力显微镜的发展历史和基本工作原理,然后重点描述qPlus型原子力显微镜技术的优势及其在单原子、单分子和低维材料体系中的应用,最后展望该技术的未来发展趋势和潜在应用。     

扫描探针显微术与纳米科技

 扫描探针显微术（ＳｃａｎｎｉｎｇＰｒｏｂｅＭｉｃｒｏｓｃｏｐｙ,ＳＰＭ）是８０年代初发展起来的一类新型的表面研究新技术,其核心思想是利用探针尖端与表面原子间的不同种类的局域相互作用来测量表面原子结构和电子结构。它的出现使得纳米科技在近十年来得到了突飞猛进的发展。１．扫描探针显微术扫描探针显微术中最早研制成功的是扫描隧道显微镜（ＳｃａｎｎｉｎｇＴｕｎｎｅｌｉｎｇＭｉｃｒｏｓｃｏｐｙ,ＳＴＭ）,它是宾尼和罗雷尔于１９８１年发明的,二人１９８６年因此被授予诺贝尔物理奖。     

超越SNOM探针通光孔径尺寸的金属纳米间隙超分辨测量

采用电磁场有限元方法,数值模拟了孔径型扫描近场光学显微镜(aperture Scanning Near-field Optical Microscopy,a-SNOM)在照明模式下的工作过程.针对金偶极天线结构,改变天线长度和纳米间隙尺寸,计算了a-SNOM探针孔径的远场辐射速率随探针端面中心坐标变化的扫描曲线,实现了超越a-SNOM探针通光孔径尺寸的天线金属纳米间隙的超分辨测量,对于100nm通光孔径的探针,可分辨最小尺寸为10nm(0.016倍波长)的金属间隙.通过对比金属和介质偶极天线的a-SNOM探针远场辐射速率测量的计算结果,表明天线金属纳米间隙的超分辨测量的实现是由于金属间隙表面等离激元的激发.     

基于半导体纳米线/锥形微光纤探针的被动式近场光学扫描成像

本文结合近场扫描结构和纳米线-微光纤耦合技术,提出了一种基于硫化镉纳米线/锥形微光纤探针结构的被动近场光学扫描成像系统.该系统采用被动式纳米探针,保留了纳米探针对样品表面反射光的强约束优势.其理论收集效率为4.65‰,相比于传统的金属镀膜近场探针收集效率提高了一个数量级,可有效地提高扫描探针对样品形貌信息的检测能力;而后通过硫化镉纳米线与微光纤之间高效的倏逝场耦合,将检测的光强信号传输到远场进行光电探测,最终实现对目标样品形貌的分析成像,其样品宽度测量误差在7.28%以内.该系统不需要外部激发光路,利用显微镜自身光源进行远场照明,被动扫描探针仅作为样品表面反射光的被动收集系统.本文基于半导体纳米线/锥形微光纤探针的被动式近场光学扫描成像方案,可有效地降低探针的制备难度和目标光场的检测难度,简化扫描成像的结构,为近场光学扫描显微系统之后的发展提供新的思路.     

扫描近场红外显微镜光纤探针的腐蚀制法

红外光探针是扫描近场红外显微镜(SNIM)中的关键部件,由于探针的种类和材料不同,制作的方法也不同.一般制作光纤探针有两种方法,即热拉伸法和化学腐蚀法.这里叙述了一种化学腐蚀方法,介绍了怎么去除砷硒碲中红外光纤的聚酰胺表层和硫化硒夹层,以及芯层腐蚀成针尖状的具体方法和过程,并对短锥针探针制法进行了探索.最后用此探针在近场范围内探测了氮化镓样品的自由电子激光(FEL)反射谱. 关键词： 扫描探针显微镜(SPM) 近场红外扫描显微镜(SNIM) 光纤探针     

A new positioning approach of fiber probe for near-field scanning optical microscope

A fiber probe-based positioning scan approach was established, whose precision can reach as high as 0.8 μm. And a set of modified microscope system was designed utilizing this approach, in which the scanning probe microscope (SPM) combined with an optical microscope was manipulated. The optical microscope and scanning probe can conveniently be switched through a switch panel. The observation period of samples can significantly be shortened. And more reliable images can be provided using this approach. Our design can effectively solve the inherent disadvantages of SPM technology, which makes SPM scan and image more reliably, conveniently, safely and rapidly.     

Simulation of Properties of Images with Atomic Resolution in a Scanning Probe Microscope

A method for simulation of images in a scanning probe microscope (SPM) using simultaneous wavelet transform and median filtering is proposed. The wavelet transform with the fourth-order Daubechies kernel is used. Such a transform makes it possible to select details of different scales in the SPM image and, hence, study fractal properties of surfaces. Simulation is used to show that ultrahigh (atomic) resolution is possible in SPM provided that the size of the contact region in the probe–sample system is significantly greater than atomic size and the lattice atoms are randomly distributed. Contrast inversion in the SPM images in the multiscan mode is interpreted.     

Effect of a charged scanned probe microscope tip on a subsurface electron gas

Using a cryogenic scanned probe microscope (SPM) one can locally modify the sheet density of a two-dimensional electron gas (2DEG), and image the ballistic flow of electrons through a point contact in the 2DEG located beneath the surface of a GaAs/AlGaAs heterostructure. We calculate the capacitively induced change in sheet density when a charged SPM tip is brought into contact with a semiconductor heterostructure containing a two-dimensional electron gas. A simple scattering model, based on a local change in sheet density, is used to analyze experimental data taken with the SPM method described above.     

Optical properties of a-C:H:Si films and their structural modifications

The measurement data on visible and UV light reflection spectra of diamondlike a-C:H:Si films and their structural modifications caused by electrical influences in a scanning probe microscope (SPM)-lithograph are presented. Numerical evaluations of the experimental data, taking into account interference effects, show that modification is of the bulk character and causes a change in the material refractive index from n ∼ 2.2 to ∼ 1.5. A decrease in the optical density of the modified material is attributed to an increase in the film porosity in the region of SPM influences.     

Fabrication of graphene nanostructures by probe nanoablation

We present the results of the study of graphene nanoablation under mechanical stress of an ultrasharp (the rounding radius is ～2 nm) tip of a scanning probe microscope (SPM)). It was found that the SPM probe contact with graphene results in average removal of 7 · 10^?3?5 · 10^?2 nm of film per scan, i.e., only a few carbon atoms or clusters, in the impact area. The capability of this precision nanoablation process was shown in developing graphene nanoislands and nanoribbons ～1 µm long and ～10 nm wide.     

New type of regular carbon nanostructures: Nanocones on the surfaces of carbon-silicon (a-C:H) composite films

The results of a study of a new type of regular carbon nanostructures, namely, nanocones on the film surfaces of carbon-silicon composites of the (a-C:H):Si type are given in this paper. Nanocones appear under the action of the electric field of the probe of an air-operated scanning probe microscope (SPM) in the case where the values of the voltage amplitude and the exposure times exceed the threshold ones. The produced nanoobjects preserve their shapes at thermal annealing up to 700°C. It is assumed that the process of nanocone formation is related to the local transformation of the carbon-silicon composite structure from the amorphous to the nanocrystalline state in the electric field of the SPM probe.     

Electronic states of self-organized InGaAs quantum dots on GaAs (3 1 1)B studied by conductive scanning probe microscope

We have used conductive scanning probe microscope (SPM) in high vacuum and operated at 173 K in order to investigate the electronic properties of self-organized InGaAs quantum dots (QDs) grown on GaAs (3 1 1)B and (0 0 1) substrates. Ordered InGaAs quantum dot arrays on GaAs (3 1 1)B surface were fabricated by atomic-H assisted molecular beam epitaxy (H-MBE), and Si SPM tips coated with Au which warrants electrical conductivity were used to measure simultaneously both the topographic and current images of QDs surface. From the current–voltage (I–V) curves, unique and different plateau features were observed for QDs formed on GaAs (3 1 1)B and (0 0 1) substrates. The results suggested that a high degree of symmetry of InGaAs QDs on (3 1 1)B was responsible for the observed degeneracy of electronic states and artificial atom-like states. We demonstrate that this conductive SPM technique becomes a powerful tool in studies of single electron charging of individual dots.     

Surface modification of porous poly(tetrafluoroethylene) film via cold plasma treatment

In this study, cold plasma technology was applied for the surface modification of porous polytetrafluoroethylene (PTFE) film to improve the hydrophilicity. The surface properties of PTFE, modified by air, helium (He) or acrylic acid (AAc), were investigated with scanning electron microscopy (SEM), scanning probe microscope (SPM), in situ X-ray photoelectron spectroscopy (XPS) and water contact angle measurements. The changes of the surface property before and after plasma treatment were discussed. According to SEM and SPM measurements, the surface roughness increased at different levels after plasma treatment. Compared to air and AAc plasma treatment, the He plasma treatment introduced large amounts of oxygen into the surface, as known from XPS results. Contact angle measurements revealed that the hydrophilicity of the PTFE film surface was greatly improved due to the surface roughness and changes of chemical elements on the PTFE surface.