Berlin 2008 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 8: Interfaces/ surfaces

HL 8.3: Talk

Monday, February 25, 2008, 14:30–14:45, EW 201

Deoxidation and surface structure of InGaN(0001) — •C. Friedrich¹, V. Hoffmann², N. Esser³, M. Kneissl¹, and P. Vogt¹ — ¹TU Berlin, Institut für Festkörperphysik, Hardenbergstr. 36, 10623 Berlin, Germany — ²Ferdinand-Braun-Institut für Höchstfrequenztechnik, Gustav-Kirchoff-Str. 4, 12489 Berlin, Germany — ³ISAS-Berlin, Albert-Einstein Str. 9, 12489 Berlin, Germany

In_xGa_1−xN alloys have attracted considerable interest due to their wide range of applications in optoelectronic devices, e.g. blue and green lasers. Although the quality of In-rich epitaxial layers has improved in recent years, there is still not much known about the atomic structure of In_xGa_1−xN surfaces. The influence of the surface structure on the growth of In_xGa_1−xN layers and on the interface formation in hetero-structures remains unclear. Here we present our results on In_xGa_1−xN surface properties after deoxidation under ultra high vacuum (UHV) conditions. Auger Electron Spectroscopy measurements of the chemical surface composition confirm residual contaminations such as carbon and oxygen even after annealing up to 600 ^∘C. Further annealing at higher temperatures leads to a strong reduction of carbon and oxygen and LEED reveals a (3×3)-surface periodicity. Scanning tunnelling microscopy (STM) measurements on such prepared surfaces show atomically flat terraces and both more metallic-like and more semi-conducting areas. Based on these results surface structure models are discussed.