Fabrication and Characterization of Dielectric and Metallic Structures with Scanning Probe Techniques

已知具有光波长量级尺寸的小结构会影响例如光的传播、吸收或发射的性质。扫描探针显微镜(SPM)在这些维度上的能力是产生和研究这样的结构。该项目将使用自建设备。它既可以作为具有静电力检测功能的扫描力显微镜(AFM)，也可以作为扫描隧道显微镜(STM)，也可以作为无孔径扫描近场光学显微镜(NSOM)。这项研究项目与研究单位的其他项目密切互动。在目前的情况下，人们已经注意到了两个主要的兴趣：我们打算在波导的顶部结构一层金属薄膜，以便在局域表面等离子体与波导模式之间产生混合模式。我们的目标是以高横向分辨率探测产生的等离子体激元场。一种可能性包括使用扫描探针显微镜作为扫描隧道显微镜来测量隧道电流的整流。同样的关于表面等离子体激元场的信息也可以通过NSOM模式获取，探测尖端散射的光。这项工作将与项目B2和C1密切合作进行。另一个目标是在微观尺度上研究和制造铁电畴。为了检测磁区结构，我们打算利用样品的压电响应并测量由此产生的厚度变化。在更高的横向分辨率下，我们将用静电力显微镜测量表面电荷的对比度。为了在铁电晶体中创建磁畴结构，我们将用扫描力显微镜的尖端对晶体局部施加电场。仅30 nm的尖端半径就能在施加中等电压的情况下达到所需的电场。在尖端下方电场强度足以切换c轴取向的区域非常小。这允许实现高空间分辨率。这些活动将与项目B1和C4的活动相协调。

Small structures with dimensions of the order of the light wavelength are known to influence the properties of, e.g., light propagation, absorption, or emission. The capabilities of scanning probe microscopy (SPM) in these dimensions are to generate as well as to investigate such structures. A selfbuilt device will be utilized for the project. It can be operated as a scanning force microscope (AFM) with the possibility of electrostatic force detection (EFM), as a scanning tunneling microscope (STM), and also as an apertureless scanning nearfield optical microscope (NSOM). This research project is in close interaction with other projects of the research unit. In the present state, two main interests can already be noted: We intend to structure a metal film on top of a waveguide in order to generate hybrid modes between localized surface plasmons and the waveguide modes. Our aim is to detect the resulting plasmon field with a high lateral resolution. One possibility consists of measuring the rectification of the tunneling current using the scanning probe microscope as a STM. The very same information about the surface plasmon field is also accessible via the NSOM mode, detecting the light scattered at the tip. This will be conducted in close collaboration with the Projects B2 and C1. Another objective is the investigation and fabrication of ferroelectric domains at the microscopic scale. For detection of the domain structures we intend to make use of the piezo response of the sample and to measure the resulting thickness changes. With even higher lateral resolution we will measure the contrast of the surface charge with electrostatic force microscopy. To create the domain structures in ferroelectric crystals we will apply an electric field to the crystal locally with the tip of the scanning force microscope. The tip radius of only 30 nm enables to reach the necessary electric field with moderate voltages applied to the tip. The area below the tip where the electric field strength is sufficient to switch the orientation of the c-axis is very small. This allows to achieve high spatial resolution. These activities will be coordinated with those of Projects B1 and C4.