Band Alignment in Lateral 2D Heterostructures

Date: 9 March 2016

Venue: UAntwerp, Campus Groenenborger, Building U, Room U.241 - Groenenborgerlaan 171 - 2020 Antwerpen

Time: 4:00 PM - 5:00 PM

Organization / co-organization: Condensed Matter Theory

Short description: Condensed Matter Theory seminar presented by Stephan Vercauteren

Band Alignment in Lateral 2D Heterostructures

The electronic band alignment in semiconductor heterostructures is a key factor for their use in electronic applications. The alignment problem has been intensively studied for bulk systems but is less well understood for low-dimensional heterostructures. Using first-principles calculations we investigate the band alignment in lateral two-dimensional heterostructures, here we take thin hydrogenated and fluorinated diamond slabs as example. Firstly, we demonstrate that great care must be taken w.r.t. the size of the vacuum region when performing these calculations. In contrast to what is generally expected, we find that in general the vacuum levels above such heterostructures are not aligned. Furthermore the alignment in these systems depends crucially on the different sizes of the heterostructure. Two limiting cases are observed: for infinitely thick heterostructures, the bandstructure on both sides is aligned, while for infinitely wide heterostructure the vacuum levels are aligned. For real systems, the alignment thus crucially depends on the ratio of these two system sizes. This behaviour is understood to be caused by the presence of a dipole at the heterostructure interface.

Stephan Vercauteren, CMT group UAntwerpen

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