Development of an Ultrafast Scanning Tunneling Microscope

将建造一台超快扫描隧道显微镜，以在超高真空中拍摄原子在短距离内的运动。通过优化仪器以用于小区域(直径小于100 A)的成像，原子分辨率成像将以每幅图像高达10毫秒的速率实现，对于完整图像，或对于窄图像，每条扫描线最高可达100微秒。这些速度比目前可用的特高压仪器快10到1000倍。该系统将在高达600摄氏度及以上的样品温度下运行，这将允许以比目前可能的更快的时间尺度观察材料表面的动态过程。样品也将通过LEED进行表征。特别是，我们将利用这台仪器研究Si(100)-2x1重构表面在退火过程中Si原子的扩散，作为分子束外延的基本原理的研究。我们还将研究Ge(111)-c(2x8)重构表面熔化过程中表面原子的运动。

An ultra fast scanning tunneling microscope will be constructed to image atomic motions over small distances in ultrahigh vacuum. By optimizing the instrument for imaging of small areas (less than 100 A across) atomic resolution imaging will be achieved at ratesup to 10 msec per image for full images, or 100 usec per scan line for narrow images. These rates are 10 to 1000 times faster than currently available UHV instruments. The system will operate at sample temperatures up to and above 600 C. This will permit the observation of dynamical processes on material surfaces with much faster timescales than is currently possible. Samples will also be characterized by LEED. In particular, we will use this instrument to study atomic diffusion of Si adatoms during annealing of the Si(100)-2x1 reconstructed surface as an investigation of the fundamentals of molecular beam epitaxy. We will also study the motion of surface atoms during melting of the Ge(111)-c(2x8) reconstructed surface.