AVS 58th Annual International Symposium and Exhibition
    Graphene and Related Materials Focus Topic Friday Sessions
       Session GR+MS+EM-FrM

Paper GR+MS+EM-FrM7
Imaging of Electron Beam Induced Current in Epitaxial Graphene

Friday, November 4, 2011, 10:20 am, Room 208

Session: Graphene Device Physics and Applications
Presenter: Shin Mou, Air Force Research Laboratory
Authors: S. Mou, Air Force Research Laboratory
J. Boeckl, Air Force Research Laboratory
W.C. Mitchel, Air Force Research Laboratory
J.H. Park, Air Force Research Laboratory
S. Tetlak, Wyle Laboratories
W. Lu, Fisk University
Correspondent: Click to Email
It has been known and observed that there forms a Schottky junction between graphene and SiC in epitaxial graphene due to the work function difference and the charge transfer between them. As a result, it is viable to apply the electron beam induce current (EBIC) technique on the epitaxial graphene directly due to the fact that it needs a built-in field and ample electron generation volume to generate EBIC. EBIC is an important characterization technique, which identifies electrically active impurities/defects, detects local built-in field, and measures minority carrier diffusion length. In this paper, we use a FEI SEM equipped with a current amplifier to investigate the spatial mapping of EBIC generation and collection in a two terminal geometry. The incident electron beam generates excited electron-hole pairs in SiC and the minority carriers are collected through the Schottky junction before flowing into graphene. EBIC imaging reveals mesoscopic domains of bright and dark contrast areas due to local EBIC polarity and magnitude, which is believed to be the result of spatial fluctuation in the carrier density in graphene. We also investigate the electron energy dependence, which modulates the EBIC magnitude. With an analytical drift-diffusion current model, we are able to extract the minority carrier diffusion length in the SiC, which is on the order of micro meter and agrees well with other published data.