Regensburg 2019 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 27: Two-dimensional Materials III (joint session HL/CPP)
HL 27.6: Talk
Wednesday, April 3, 2019, 10:45–11:00, H36
Electric field control of interlayer excitons in MoS2/WS2 heterobilayers — •Fabian Kronowetter1, Jonas Kiemle1, Florian Sigger1,2, Alexander Holleitner1,2, and Ursula Wurstbauer1,2,3 — 1Walter Schottky Institut and Physics-Department, Technical University of Munich, Germany — 2Nanosystems Initiative Munich (NIM), Germany — 3Institute of Physics, WWU Münster, Germany
Ensembles of interlayer excitons (IXs) are intriguing systems to explore classical and quantum phases of interacting bosonic ensembles with enlarged lifetimes due to reduced overlap of the electron-hole wave functions. We demonstrate electric field control of the IX in MoS2/WS2 heterobilayer embedded in a field effect structure with few layer hexagonal boron nitrite (hBN) as insulator and few-layer graphene as gate-electrodes. We observe a multiplet structure in the IX emission band even at room temperature. Stark shift measurements reveal the presence of a finite out-of plane dipole of the IX. The different strength of the dipole and a distinct temperature dependence identify the IXs to stem from optical interband transitions with electrons and holes located in different valleys of the heterostructures. For the lowest emission line, we observe field dependent level anti-crossing at low temperatures. We discuss this behavior in terms of coupling of electronic states from the two TMDC monolayers. Our results demonstrate the design of novel nano-quantum materials prepared from artificial van der Waals solids with the possibility to in-situ control their physical properties via external stimuli such as electric fields.