High-resolution core-level photoemission measurements on the pentacene single crystal surface assisted by photoconduction

作者：Nakayama Yasuo^*; Uragami Yuki; Yamamoto Masayuki; Yonezawa Keiichirou; Mase Kazuhiko; Kera Satoshi; Ishii Hisao; Ueno Nobuo

来源：Journal of Physics: Condensed Matter , 2016, 28(9): 094001.

DOI：10.1088/0953-8984/28/9/094001

• organic semiconductor
• electrical insulator
• x-ray photoelectron spectroscopy
• synchrotron radiation
• surface oxidation

Upon charge carrier transport behaviors of high-mobility organic field effect transistors of pentacene single crystal, effects of ambient gases and resultant probable 'impurities' at the crystal surface have been controversial. Definite knowledge on the surface stoichiometry and chemical composites is indispensable to solve this question. In the present study, high-resolution x-ray photoelectron spectroscopy (XPS) measurements on the pentacene single crystal samples successfully demonstrated a presence of a few atomic-percent of (photo-) oxidized species at the first molecular layer of the crystal surface through accurate analyses of the excitation energy (i.e. probing depth) dependence of the C1s peak profiles. Particular methodologies to conduct XPS on organic single crystal samples, without any charging nor damage of the sample in spite of its electric insulating character and fragility against x-ray irradiation, is also described in detail.

• 出版日期2016-3-9