A Morphological Study of Highly Oriented Pyrolytic Graphite at Atomic Level Using Scanning Tunneling Microscopy
Date of Graduation
Master of Science in Materials Science
Physics, Astronomy, and Materials Science
scanning tunneling microscopy, introduction to STM, STM of HOPG, surface characterization by STM, modes of operation in STM
Materials Science and Engineering
Scanning tunneling microscopy (STM) has been applied extensively to study the composition and distribution of molecules or nanostructures assembled on a surface. In this technique, a sophisticated electronic feedback system is combined with a piezoelectrically mounted, conductive tip to probe the sample surface. The STM tips were made of platinum/ iridium wire using a mechanical cutting procedure towards a rank of atomic sharpness, while the surface of highly oriented pyrolytic graphite was prepared by cleaving. Image quality of STM micrographs depends greatly on the properties of the tip and the control parameters of the feedback system. By applying a gape voltage of 10̃200 mV and a feedback current of 5̃50 nA, we have achieved atomic resolution at room temperature under ambient conditions. The symmetry of graphite unit cells is clearly resolved under STM. Atomic force microscopy (AFM) images of the same samples are presented for comparison, as will scanning electron microscopy (SEM) images of atomically sharp tips used in the STM experiments.
© Rakesh N.T.V. Janardhan
Janardhan, Rakesh N.T.V., "A Morphological Study of Highly Oriented Pyrolytic Graphite at Atomic Level Using Scanning Tunneling Microscopy" (2006). MSU Graduate Theses. 1574.