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HL: Fachverband Halbleiterphysik

HL 74: Poster IIIA

HL 74.13: Poster

Donnerstag, 19. März 2020, 15:00–17:30, P2/2OG

Benchmarking calculated excited state properties of 2D materials on substrates and in van de Waals heterostructures against experiments — •Anders Christian Riis-Jensen and Kristian Sommer Thygesen — Technical University of Denmark, Institute of Physics

2D materials and van der Waals heterostructures exhibit extraordinary optical properties because of the reduced screening in two dimensional materials. Due to the possible lattice mismatch and relative twist angle between the layers constituting a van der Waals heterostructure, accurate many-body ab-initio calculations for such many layers heterostructures are not possible.

By combining many-body ab-initio calculations with electrostatic and perturbative models, we calculate quasi-particle band gaps and intra- and interlayer exciton energies in many layers van der Waals heterostructures, and benchmark to what accuracy these properties can be calculated compared to experimental measurements. Furthermore, we show what discrepancy can be expected between ab-initio calculations and experiments for optical properties due to the effect of substrate screening and show how the screening of 2D materials on bulk substrates can be accurately modelled by a generalized analytical 2D hydrogen model. At the end of the talk I will discuss a new screening regime for 2D materials on strongly screening substrates, where the exciton behavior is very different from the well-known picture in 2D materials and van der Waals heterostructures.