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Lookup NU author(s): Dr Aleksey KozikovORCiD
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
Band structure engineering using alloying is widely utilized for achieving optimized performance in modern semiconductor devices. While alloying has been studied in monolayer transition metal dichalcogenides, its application in van der Waals heterostructures built from atomically thin layers is largely unexplored. Here, heterobilayers made from monolayers of WSe 2 (or MoSe 2 )and MoxW 1 − xSe2 alloy are fabricated and nontrivial tuning of the resultant band structure is observed as a function of concentration x. This evolution is monitored by measuring the energy of photoluminescence (PL) of the interlayer exciton (IX) composed of an electron and hole residing in different monolayers. In MoxW 1 − xSe2 /WSe2 , a strong IX energy shift of ≈100 meV is observed for x varied from 1 to 0.6. However, for x < 0.6 this shift saturates and the IX PL energy asymptotically approaches that of the indirect bandgap in bilayer WSe 2 . This observation is theoretically interpreted as the strong variation of the conduction band K valley for x > 0.6, with IX PL arising from the K − K transition, while for x < 0.6, the band structure hybridization becomes prevalent leading to the dominating momentum-indirect K − Q transition. This band structure hybridization is accompanied with strong modification of IX PL dynamics and nonlinear exciton properties. This work provides foundation for band structure engineering in van der Waals heterostructures highlighting the importance of hybridization effects and opening a way to devices with accurately tailored electronic properties.
Author(s): Catanzaro A, Genco A, Louca C, Ruiz-Tijerina DA, Gillard DJ, Sortino L, Kozikov A, Alexeev EM, Pisoni R, Hague L, Watanabe K, Taniguchi T, Ensslin K, Novoselov KS, Fal'ko V, Tartakovskii AI
Publication type: Article
Publication status: Published
Journal: Advanced Materials
Year: 2024
Volume: 36
Issue: 19
Online publication date: 26/01/2024
Acceptance date: 08/01/2024
Date deposited: 27/06/2024
ISSN (print): 0935-9648
ISSN (electronic): 1521-4095
Publisher: Wiley
URL: https://doi.org/10.1002/adma.202309644
DOI: 10.1002/adma.202309644
Data Access Statement: The data that support the findings of this study are available from the corresponding author upon reasonable request
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