Berlin 2024 – scientific programme
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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 Bolotin1 — 1Physics 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