Berlin 2015 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 81: Heterostructures and interfaces

HL 81.3: Talk

Thursday, March 19, 2015, 15:30–15:45, EW 201

Band alignment in lateral two-dimensional heterostructures — Stephan Vercauteren, Ortwin Leenaerts, Bob Schoeters, and •Bart Partoens — University of Antwerp, Department of Physics, Belgium

The properties of semiconductor interfaces is mainly determined by the alignment of their respective band structures. Various methodologies have been devised to obtain the band alignment for bulk semiconductors, ranging from the simple alignment of vacuum potentials to the explicit simulation of the heterostructure with first-principles methods. When the dimensionality of the semiconductors is reduced, several problems with these alignment methods arise. Especially in-plane heterostructures, which consist of laterally connected 2D crystals, are more difficult to treat. Naive reasoning suggests that the simple alignment of the vacuum levels above each material is sufficient to determine the band alignment, but this simple reasoning is incorrect. We demonstrate that the vacuum potential is generally different above different 2D materials and that this difference depends crucially on the thickness of the involved materials. Furthermore, care should be taken to obtain the band alignment through heterostructure modeling with first-principles methods. The boundary conditions have a strong impact on the band alignment which needs to be corrected for.