Regensburg 2022 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 64: Gerhard Ertl Young Investigator Award
O 64.5: Vortrag
Donnerstag, 8. September 2022, 12:30–13:00, S051
Efficient electronic passivation schemes for surface calculations of semiconductors exhibiting spontaneous polarization: Thermodynamic and electronic properties of GaN surfaces — •Su-Hyun Yoo1, Mira Todorova1, Liverios Lymperakis1, Chris Van de Walle2, and Jörg Neugebauer1 — 1Department of Computational Materials Design, MPI für Eisenforschung, Germany — 2Computational Materials Group, Materials Department, UCSB, USA
Semiconductor surfaces play a central role in modern technology related to catalysis, electronics, and energy applications. The most widespread approach to study surfaces with density-functional theory calculations is to use slab geometries with periodic boundary conditions. A common strategy employed to avoid artificial charge transfer from one side of the slab to another, is to passivate the dangling bonds at its backside. Using the examples of wurtzite polar and semipolar surfaces, we demonstrate that the conventional passivation scheme using pseudo-H atoms fails to describe the electronic structure of low-symmetry semiconductors. We therefore developed an improved passivation method [npj Comp. Mater. 7, 58, 2021/PR Mater. 5, 044605, 2021] that takes the polarization effect and the concept of surface reconstructions into account. It accurately describes surface electronic properties and enables computationally efficient surface energy calculations. Using this novel approach we have studied the orientation-dependent thermodynamic stability and electronic properties of GaN surfaces. The resulting Wulff shape provides insight of how to avoid facet-related defects such as V-pits hampering GaN-based electronics.