Dresden 2009 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 42: Interfaces/surfaces
HL 42.4: Vortrag
Donnerstag, 26. März 2009, 10:15–10:30, POT 51
Surface states and origin of the Fermi level pinning on non-polar GaN(1100) surfaces — •Lena Ivanova1, Svetlana Borisova2, Holger Eisele1, Mario Dähne1, Ansger Laubsch3, and Philipp Ebert2 — 1Institut für Festkörperphysik, Technische Universität Berlin, 10623 Berlin, Germany — 2Institut für Festkörperforschung, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany — 3OSRAM Opto-Semiconductors GmbH, 93055 Regensburg, Germany
Group-III nitrides raised considerable attraction because of their ideal properties for green, blue, and ultraviolet laser and LED devices. One particular challenge of the epitaxial growth is the impurity, dopant, and defect incorporation during growth, which often depends on the position of the Fermi level at the growth surface. For the non-polar GaN surfaces only little is known about the exact positions of the surface states and thus their possible influence on the Fermi energy.
Therefore, we investigated GaN(1100) cleavage surfaces by cross-sectional scanning tunneling microscopy and spectroscopy [1]. We identified the energy positions and types of surface states as well as the origin of the Fermi level pinning on GaN(1100) cleavage surfaces. It is found that both the N and Ga derived intrinsic dangling bond surface states are outside of the fundamental band gap. The observed Fermi level pinning 1.0 eV below the conduction band edge is attributed to the high step and defect density at the surface but not to intrinsic surface states.
[1] L. Ivanova et al., APL 93, 192110 (2008).
This work is supported by the DFG.