Berlin 2018 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 14: 2D Materials: Session II (joint session DS/CPP/HL)
HL 14.6: Vortrag
Dienstag, 13. März 2018, 10:45–11:00, H 2032
Suppression of excitonic absorption in few-layer GaSe — •Arne Budweg1, Dinesh Yadav1,2, Alexander Grupp1, Alfred Leitenstorfer1, Maxim Trushin1,3, Fabian Pauly1,2, and Daniele Brida1 — 1Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457 Konstanz, Germany — 2Okinawa Institute of Science and Technology Graduate University, Onna-son, Okinawa 904-0395, Japan — 3Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, Singapore 117546
We study the thickness dependent optical absorption of GaSe via highly sensitive differential transmission measurements. Controlling the number of individual layers in a GaSe nanosheet, we observe a suppression of the excitonic transition below a critical value of 8. Ab-initio modelling enables us to attribute this behavior to a fundamental change in the band structure which, in thin GaSe, leads to a valence band shaped as an inverted Mexican hat. The observed modulation of the optical properties is intrinsic and does not require control via external parameters like substrate material or an applied electric field. Therefore GaSe provides attractive resources for the development of functional optoelectronic devices based on a single material.