AVS 47th International Symposium
    Electronics Tuesday Sessions
       Session EL+NS-TuM

Paper EL+NS-TuM6
Characterization of Gold/Pentacene and Pentacene/Gold Interfaces

Tuesday, October 3, 2000, 10:00 am, Room 312

Session: Molecular Electronics
Presenter: N.J. Watkins, University of Rochester
Authors: Q.T. Le, University of Rochester
S. Zorba, University of Rochester
E.F. Forsythe, University of Rochester
L. Yan, University of Rochester
N.J. Watkins, University of Rochester
Y. Gao, University of Rochester
S.F. Nelson, Colby College
C.S. Kuo, The Pennsylvania State University
T.N. Jackson, The Pennsylvania State University
Correspondent: Click to Email
Among the conjugated oligomers used as active materials in the fabrication of organic thin-film transistors (OTFT), pentacene is one of the most promising materials due to its high field-effect mobility. The performance of pentacene based OTFTs is now comparable to that obtained from hydrogenated amorphous silicon TFTs. The interface formed between the organic semiconductor and the conducting layer strongly influences the current-voltage characteristics of OTFTs. We report the interface formation between gold (Au) and pentacene using x-ray and ultraviolet photoelectron spectroscopy (XPS and UPS). The morphology of the pentacene film deposited on the substrate was measured using atomic force microscopy, showing a pentacene layer with small grain size. XPS results indicate that Au does not chemically react with pentacene if Au is deposited onto pentacene or if pentacene is deposited onto Au. For Au deposited on pentacene the UPS results show that there is an initial binding energy shift of both the highest occupied molecular orbital of pentacene and the vacuum level attributed to the formation of a common fermi level for the Au and pentacene as the Au is deposited. The initial increase is then followed by a decrease in binding energy shifts that is attributed to a reduction of the polarization energy caused by the formation of a Au overlayer on the surface of the pentacene. For pentacene deposited onto Au the UPS results show that there is only a shift of the vacuum level to lower binding energy.shift of the vacuum level to lower binding energy.