Berlin 2015 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 11: Transition-metal dichalcogenides and boron nitride (with O)

HL 11.4: Talk

Monday, March 16, 2015, 12:30–12:45, ER 270

Low-temperature photoluminescence of 2D Dichalcogenides and indirect excitons in their heterostructures — •Philipp Nagler¹, Gerd Plechinger¹, Philipp Tonndorf², Steffen Michaelis de Vasconcellos², Rudolf Bratschitsch², Christian Schüller¹, and Tobias Korn¹ — ¹Institut für Experimentelle und Angewandte Physik, Universität Regensburg, 93040, Regensburg, Germany — ²Physikalisches Institut, Westphälische Wilhelms-Universität Münster, 48149, Münster, Germany

Two-dimensional transition-metal dichalcogenides (TMD) have recently emerged as a promising class of direct-gap semiconductors. Here, we present low-temperature photoluminescence (PL) measurements of four different monolayer TMDs, namely MoS₂, MoSe₂, WS₂ and WSe₂. The diselenides show a clear splitting of neutral exciton and trion which enables us to deduce the binding energy of the trion. Furthermore, by using a deterministic transfer technique we are able to fabricate van-der-Waals heterostructures consisting of different 2D TMDs. At room temperature, we observe indirect excitons at the interface which probably stem from a spatial separation of electrons and holes. Power-dependent PL measurements on the heterostructures allow us to alter the excitonic regime and to probe saturation effects of the system.