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HL: Fachverband Halbleiterphysik
HL 17: Organic Semiconductors
HL 17.9: Talk
Tuesday, March 19, 2024, 11:45–12:00, EW 015
Direct observation of the energy band structure of the super atom molecular orbital in solid phase C60 — •Daichi Homma1, Susumu Yanagisawa2, and Hiroyuki Yoshida1,3 — 1Graduate School of Engineering, Chiba University, Chiba, Japan — 2Faculty of Science, University of the Ryukyus, Okinawa, Japan — 3Chiba University MCRC, Chiba, Japan
The Super Atom Molcular Orbital (SAMO) is a hydrogen-like unoccupied orbital in which an electron is loosely bound around a central Coulomb potential of a molecule. Because of this nature, SAMO is predicted to form nearly free electron (NFE) bands in solids, which should exhibit high electron mobility. SAMO was first observed in C60 [1] and has so far only been observed in the monolayer and in the gas phase. To discuss the electron mobility in the solid phase, it is essential to detect the SAMO and measure the band structure in the solid state.
Recently, we have developed angle-resolved low-energy inverse photoelectron spectroscopy [2]. Using this technique, we observed the s-SAMO of C60 in bulk for the first time and further revealed the band structure. We prepared a 10 nm thick epitaxially grown C60 film on the Cu(111). From the comparison with the previous studies, we assigned a peak 2.97eV above the LUMO band as the SAMO-derived band. The observed band structure is NFE-like with an effective mass of 1.35 me. [1] M. Feng, et al., Science 320, 359 (2008). [2] Y. Kashimoto, et al., Rev. Sci. Instrum. 94, 063903 (2023).
Keywords: low-energy inverse photoelectron spectroscopy; energy band structure; super atom molcular orbital; nearly free electron band; effective mass