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O: Oberflächenphysik
O 40: Halbleiteroberflächen und -grenzflächen
O 40.11: Vortrag
Donnerstag, 11. März 2004, 18:15–18:30, H45
Angle-resolved photoelectron spectroscopy of CuInSe2(001) — •Ralf Hunger1, Wolfram Jaegermann1, Wolfram Calvet2, Carstan Lehmann2, Christian Pettenkofer2, Keiichiro Sakurai3, and Shigeru Niki3 — 1Surface Science Division, TU Darmstadt, 64287 Darmstadt — 2Abt. Heterogrenzflächen, HMI, 14109 Berlin — 3Thin Film Solar Cells Group, AIST, Tsukuba 805-8568, Japan
We have investigated the valence band structure of CuInSe2 by angle-resolved photoelectron spectroscopy (ARPES). Heteroepitaxial CuInSe2(001)/GaAs films were prepared by molecular beam epitaxy which and covered by a protective selenium cap. In the UHV analysis system, clean and ordered CuInSe2(001) surfaces were prepared by thermal desorption of the Se cap layer. This surfaces exhibited a (1 × 1)-LEED pattern and MgK α -ecited XPS proved the surface to be free of oxygen and hydrocarbon contamination. ARPES experiments were conducted at the TGM7 beamline at Bessy2 using a VG ADES500 analyser.
The final state bands were investigated by EDCs in normal emission ( Γ T direction in the tetragonal chalcopyrite lattice) using excitation energies from h ν = 9.6 eV to h ν = 40 eV. A transition from the top of the valence band (VBM) at Γ to a free-electron like final state band was observed for h ν = 11.3 eV. Thereby, the inner potential V0 was determined to −6.9 eV and the VBM lies at 0.4 eV. Angular scans were performed along the Γ X ([110]) and Γ M ([010]) directions with h ν = 21.2 eV. The resulting experimental band structure will be presented and compared to calculations by Jaffe&Zunger (PRB 28 (1983) p. 5822).