AVS 59th Annual International Symposium and Exhibition
    Graphene and Related Materials Focus Topic Thursday Sessions
       Session GR-ThP

Paper GR-ThP6
Layer Dependent Growth of Pentacene on Epitaxial Graphene

Thursday, November 1, 2012, 6:00 pm, Room Central Hall

Session: Graphene and Related Materials Poster Session
Presenter: W. Jung, Sungkyunkwan University, Republic of Korea
Authors: W. Jung, Sungkyunkwan University, Republic of Korea
D.-H. Oh, Sungkyunkwan University, Republic of Korea
J. Lee, Sungkyunkwan University, Republic of Korea
B.G. Shin, Sungkyunkwan University, Republic of Korea
C.-Y. Park, Sungkyunkwan University, Republic of Korea
J.R. Ahn, Sungkyunkwan University, Republic of Korea
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Graphene have showed promising performance as electrodes of organic devices such as organic transistors, light-emitting diodes, and photovoltaic solar cells. In particular, among various organic materials of graphene-based organic devices, pentacene has been regarded as one of promising organic materials because of its high mobility, chemical stability, and compatibility with a low-temperature silicon processing. In the development of graphene-based organic devices, it is thus important to understand an interaction of pentacene with graphene. In this study, we focused on how the growth of pentacene depends on an interaction between graphene and a substrate. Epitaxial graphene grown on a 6H-SiC(0001) surface was used as a pristine graphene because zeroth-layer graphene, called a buffer layer, and monolayer graphene have the same graphene structure but zeroth-layer graphene, which bonds strongly to a SiC substrate, has different electronic properties from monolayer graphene. We have studied how graphene grows differently at room temperature on monolayer graphene in comparison to zeroth-layer graphene using scanning tunneling microscopy and first principles calculations. On the zeroth-layer graphene, pentacene was adsorbed on specific sites with three different orientations but did not show a long-range order. In contrast to zeroth-layer graphene, pentacene forms a two dimensional ordered structure on monolayer graphene. The orientation of pentacene in the ordered structure was determined by the zigzag direction of the edge structure of monolayer graphene. The short-range and long-range ordering on zeroth-layer and monolayer graphene, respectively, was understood by different energetics of pentacene on zeroth-layer from monolayer graphene, where a total energy of pentacene on graphene was calculated by first principles calculations.