AVS 60th International Symposium and Exhibition
    Scanning Probe Microscopy Focus Topic Friday Sessions
       Session SP+AS+EM+GR+MI+NS+SS-FrM

Paper SP+AS+EM+GR+MI+NS+SS-FrM1
STM Mapping of Thermoelectric Power on Graphene across Defects and Boundaries

Friday, November 1, 2013, 8:20 am, Room 202 C

Session: Probing Electronic and Transport Properties
Presenter: J. Park, Oak Ridge National Laboratory
Authors: J. Park, Oak Ridge National Laboratory
G. He, Carnegie Mellon University
R.M. Feenstra, Carnegie Mellon University
A.P. Li, Oak Ridge National Laboratory
Correspondent: Click to Email
We present the spatially resolved thermoelectric power on epitaxial graphene on SiC by a scanning tunneling microscopy (STM) method. A thermovoltage is induced by a temperature difference between tip and sample and variations of thermovoltage are distinguished at defects and boundaries with atomic resolution. The epitaxial graphene shows a high thermoelectric power of 42 µV/K with a big change (9.6 µV/K) at the monolayer-bilayer boundary. Also, the thermopower is modified by Friedel oscillations of the charge density in graphene. Besides the change at the monolayer and bilayer graphene boundary, the thermopower also provides spectroscopy maps which reveal domain structures induced by collapsed graphene wrinkles that not obvious in STM images. The thermopower distribution measurement with STM thus allows probing the electronic, thermoelectric, and structural properties down to the individual defect level.