Atomic force microscope

我们申请了一种自动化原子力显微镜，它以一种无破坏的方式表征固体表面。典型的样品有半导体晶体、量子点和二维材料。这是一台显微镜，通过原子力显微镜（AFM）在真实空间中对样品的表面结构进行成像，横向分辨率为纳米级，纵向分辨率为亚纳米级。为此，将一个非常锋利的尖端靠近表面，并测量其与表面的相互作用力。这种力是通过支撑尖端的悬臂梁的弹性变形来评估的。通过尖端的逐行移动和逐像素存储高度信息来扫描预定义区域。如果尖端和表面之间的距离由足够快的反馈回路调节，该仪器不接触表面，因此不能改变或破坏它。如果仪器能够自行接近和测量预定区域，则可以以自动化方式测量整个晶圆。测量的区域是自动识别的标志，允许可重复检索，从而与其他实验在相同的样品进行比较。除了地形信息外，还可以记录功能图像。这些可以由结构的机械和电气性能组成。原子力显微镜将表征分子束外延生长的样品，这对许多不同的项目都很重要。其中之一是周期性调制表面结构的成像，这种结构是由生长梯度形成的，并导致自组织量子点（SAQD）的横向定位。材料对比成像将有助于分析这些表面上控制量子点成核的扩散。在进一步的项目中，离子注入半导体的表面将被研究。通过局部液滴刻蚀，制备出量子点，用于量子信息研究，并通过原子力显微镜对量子点进行可视化分析。最后，混合二维半导体将被制造和研究。表面原子力显微镜是研究外延层最重要的方法之一。到目前为止，我们在对外合作中进行了一些这样的调查。然而，为了缩短下一个生长过程的反馈循环，我们需要对晶圆上的大面积进行标准分析。这就是为什么现代自动化原子力显微镜在我们的研究中是绝对必要的。

We apply for an automatized atomic force microscope which characterizes the surface of solids in a destruction-free manner. Typical samples are semiconductor crystals, quantum dots and 2D materials. This is a microscope, which images the surface structures of samples, laterally with nanometer and vertically with sub-nanometer resolution in real space by AFM (atomic force microscopy). To this end, a very sharp tip is brought close to the surface and its interaction force with the surface is measured. This force is evaluated by elastic deformation of a cantilever, which supports the tip. A predefined area is scanned by a line-wise movement of the tip and the storage of the height information pixel by pixel. The instrument does not touch the very surface and therefore cannot alter or destroy it, if the distance between tip and surface is regulated by a fast enough feedback loop. Whole wafers can be measured in an automatized manner if the instrument is capable of by approaching and measuring predefined areas on its own. The measured areas are automatically identified by landmarks which allow to reproducibly retrieve and thus to compare them with other experiments on the same sample. Beside the topographic information even functional images can be recorded. These can consist of mechanical and electrical properties of the structures. The AFM will characterize molecular beam epitaxy grown samples which is important for many different projects. One of them is the imaging of periodically modulated surface structures which are formed by a growth gradient and lead to a lateral positioning of self-organized quantum dots (SAQD). Material contrast imaging will help to analyze the diffusion on such surfaces which governs the nucleation of the quantum dots. In a further project, the surface of ion implanted semiconductors will be studied. By local droplet etching, quantum dots are fabricated for quantum information research which will also be visualized and analyzed by the AFM. Finally, hybrid 2D-semiconductors will be fabricated and investigated. AFM of surfaces is one the most important investigation methods of epitaxial layers. Up to now, we performed some investigations of this kind in external cooperations. However, we need a standard analysis of large areas on our wafers in order to shorten the feedback loop for the next growth process. That is why a modern and automatized AFM is absolutely necessary in our research.