Compact coarse approach mechanism for scanning tunneling microscope

We report on the design and fabrication of a coarse approach mechanism, called a piezotube walker, based on a piezoelectric tube moving inside a triangular prism shaped cavity. This walker walks like a six legged insect moving its legs one by one and then the belly following. The walker works in any orientation from horizontal to vertical and its motion is found to be linear with the applied voltage above a threshold voltage. A compact scanning tunneling microscope (STM) was fabricated using this approach mechanism. The scanner tube of the STM is mounted on the inside of the walker tube, reducing the size of the STM considerably. Topographical images with atomic resolution were obtained for layered materials like graphite and NbSe2. (C) 2001 American Institute of Physics.