Regensburg 2007 – scientific programme

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O: Fachverband Oberflächenphysik

O 59: Oxides and Insulators: Clean Surfaces

O 59.12: Talk

Thursday, March 29, 2007, 18:30–18:45, H41

Band mapping the ZnO(1120) surface by angle-resolved photoelectron spectroscopy — •Stefan Andres, Christian Pettenkofer, Wolfgang Bremsteller, and Joachim Wider — Hahn-Meitner-Institut GmbH, Berlin, Deutschland

Zinc oxide (ZnO) is a transparent, piezoelectric semiconductor. Its large band gap of about 3.4eV and high exciton binding energy of about 60meV render ZnO an interesting material for optoelectronic devices in the UV-regime. Furthermore the piezoelectric properties can be utilized in SAW-devices.

Recent studies have shown that the ZnO(1120) surface is a promising candidate for such devices.

We present angle resolved photoemission data from an in-situ cleaved, (1120) oriented ZnO single crystal as well as from epitaxially grown thin ZnO(1120) films. The spectra were recorded at the TGM7 beamline at BESSYII synchrotron light facility in Berlin.

It is shown, that the surface electronic structure of both the epitaxially thin films and the single crystal coincide with each other. The band dispersion along k_⊥ and k_∥ is discussed in accordance with theoretical band structure calculations.

For the Γ−X′ direction a new band, centered at X′ is observed which is tentatively assigned to a surface-Umklapp process.