Energy level alignment between C60 and Al using ultraviolet photoelectron spectroscopy

• Published in: Applied surface science 2006-09, Vol.252 (22), p.8015-8017
• Main Authors: SEO, J. H, KANG, S. J, KIM, C. Y, CHO, S. W, YOO, K.-H, WHANG, C. N
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electron and ion emission by liquids and solids; impact phenomena; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; Photoemission and photoelectron spectra; Physics; Surface and interface electron states; Surface states, band structure, electron density of states
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2005.12.095

The energy level alignment between C60 and Al has been investigated by using ultraviolet photoelectron spectroscopy. To obtain the interfacial electronic structure between C60 and Al, C60 was deposited on a clean Al substrate in a stepwise manner. The valence-band spectra were measured immediately after each step of C60 deposition without breaking the vacuum. The measured onset of the highest occupied molecular orbital energy level was located at 1.59eV from the Fermi level of Al. The vacuum level was shifted 0.68eV toward lower binding energy with additional C60 layers. The observed vacuum level shift means that the interface dipole exists at the interface between C60 and Al. The barrier height of electron injection from Al to C60 is 0.11eV, which is smaller value than that of hole injection.