Regensburg 2025 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 59: 2D Semiconductors and van der Waals Heterostructures VI

HL 59.3: Talk

Friday, March 21, 2025, 10:00–10:15, H15

Twisted MoSe2 Homobilayer Behaving as a Heterobilayer — •Arka Karmakar — Institute of Experimental Physics, Faculty of Physics, University of Warsaw, 02-093 Warsaw, Poland

Heterostructures (HSs) formed by the transition-metal dichalcogenides (TMDCs) materials have shown great promise in next-generation (opto)electronic applications. Traditionally, at atomically closed proximity the charge transfer (CT) process dominates due to its fast timescale (< 50 fs). In this talk, I introduce our latest work [1] on the ET process in a twisted molybdenum diselenide (MoSe2) homobilayer without any charge-blocking interlayer, i.e., in atomically closed proximity. We fabricated an unconventional homobilayer (i.e., HS) with a large twist angle (~57°) by combining the chemical vapor deposition (CVD) and mechanical exfoliation (Exf.) techniques to fully exploit the lattice parameters mismatch and indirect/direct (CVD/Exf.) bandgap nature. These result in weakening the CT process and allowing the ET process to take over the carrier recombination channels. We employ a series of optical and electron spectroscopy techniques, complementing by the density functional theory (DFT) calculations, to describe a massive room temperature photoluminescence enhancement from the HS area due to an efficient ET process. Our results show that the electronically decoupled MoSe2 homobilayer is coupled by the ET process, mimicking a 'true' heterobilayer nature.

Reference: [1] A. Karmakar et al., ''Twisted MoSe2 Homobilayer Behaving as a Heterobilayer'', Nano Lett. 2024, 24, 31, 9459-9467.

Keywords: Exciton; Energy Transfer; Charge Transfer; TMDC; Heterostructure