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HL: Halbleiterphysik
HL 38: Poster 2
HL 38.61: Poster
Donnerstag, 14. März 2002, 16:30–19:00, Poster A
Inverse Photoemission Measurements on Phthalocyanines Grown on S-passivated GaAs — •Mihaela Gorgoi, Thorsten U. Kampen, and Dietrich R. T. Zahn — Institut für Physik, Technische Universität Chemnitz, D-09107
The lowest unoccupied states of phthalocyanines (Pc) thin films grown on S-passivated GaAs(100) are investigated using inverse photoemission spectroscopy (IPES). Sulphur-passivation of the substrate was achieved by wet chemical etching in S_2Cl2 and CCl_4. The Pc films were grown onto the substrates by organic molecular beam deposition. The low energy electron gun used for the excitation of the IPES spectra was constructed following an Erdman and Zipf [1] design and has an energy range from 0 eV to 16.5 eV. The Geiger-Müller counter [2] uses dimethyl ether as a detector gas and a MgF window, resulting in a bandpass energy of 10.6 eV. The unoccupied states are recorded as a function of the film thickness. In combination with the highest occupied states recorded by photoemission spectroscopy the distance between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital LUMO) is determined and compared with the band gap obtained from optical measurements. [1] P. W. Erdman, E. C. Zipf, Rev. Sci. Instrum. 53, 225 (1982) [2] K. Prince, Rev. Sci. Instrum. 59 (5) 741 (1988)