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HL: Fachverband Halbleiterphysik

HL 9: 2D Materials and Heterostructures: Interlayer Excitons

HL 9.1: Talk

Monday, March 18, 2024, 15:00–15:15, EW 201

New interlayer excitons in 2D bilayers revealed under strong electric field — •Sviatoslav Kovalchuk1, Kyrylo Greben1, Abhijeet Kumar1, Simon Pessel1, Jan Soyka2, Qing Cao2, Kenji Watanabe3, Takashi Taniguchi3, Dominik Christiansen4, Malte Selig4, Andreas Knorr4, Siegfried Eigler2, and Kirill Bolotin11Physics Department, FU Berlin, Berlin — 2Institute of Chemistry and Biochemistry, FU Berlin, Berlin — 3National Institute for Materials Science, Tsukuba, Japan — 4Physics Department, TU Berlin, Berlin

Excitons in bilayer transition metal dichalcogenides (2L-TMDs) are Coulomb-bound electron/hole pairs that can be viewed as broadly tunable analogs of atomic or molecular systems. Here, we study the properties of 2L-TMD excitons under a strong electric field. To overcome the field limit reached in previous experiments, we developed a new organic/inorganic molecular gating technique. This approach allows us to achieve an electric field strength of about 0.35 V/nm, more than a factor of two higher than achieved previously in purely solid-state gated devices. Under this field, inter- and intralayer excitons are brought into an energetic resonance, allowing us to discover new emergent properties of the resulting states. We detect a previously unseen interlayer exciton that only becomes visible at high field through hybridization with A exciton. Moreover, the system experiences an ultra-strong Stark splitting of > 380 meV with exciton energies tunable over a large range of the optical spectrum, holding potential for optoelectronics.

Keywords: TMD; Electric field; Doping molecules; bilayer; Stark effect

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