Regensburg 2010 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 27: GaN Preparation and Characterization
HL 27.6: Vortrag
Dienstag, 23. März 2010, 15:15–15:30, H15
Doping modulation in GaN investigated by cross-sectional scanning tunneling microscopy — Holger Eisele1, Lena Ivanova1, Svetlana Borisova2, Mario Dähne1, Momme Winkelnkemper1, and •Philipp Ebert2 — 1Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany — 2Institut für Festkörperforschung, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
Cross-sectional scanning tunneling microscopy (XSTM) of III-V semiconductor structures on cleavage planes is a powerful technique providing a direct access to the atomically resolved geometric and electronic structure of semiconductor interfaces. Unfortunately, thus far XSTM has been only applied successfully to zincblende type materials. Here we investigated for the first time the imaging mechanisms of a Si doping modulation in wurtzite-structure GaN by cross-sectional scanning tunneling microscopy. The Si doping modulation gives rise to a voltage and tip dependent height modulation of at least 0.04 nm. The origin of the height modulation in constant-current STM images is traced to two mechanisms. A doping-induced modulation of the band edge energies yields a voltage dependent electronic contrast and an additional mechanical relaxation of the doping-induced strain at the cleavage surface is responsible for a voltage independent modulation of 0.035 nm.