Effect of Distance on Photoluminescence Quenching and Proximity-Induced Spin-Orbit Coupling in Graphene/WSe 2 Heterostructures

• Published in: Nano letters 2018-06, Vol.18 (6), p.3580-3585
• Main Authors: Yang, Bowen, Molina, Everardo, Kim, Jeongwoo, Barroso, David, Lohmann, Mark, Liu, Yawen, Xu, Yadong, Wu, Ruqian, Bartels, Ludwig, Watanabe, Kenji, Taniguchi, Takashi, Shi, Jing
• Format: Article
• Language: English
• Subjects: Chemistry; Materials Science; Physics; Science & Technology - Other Topics
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/acs.nanolett.8b00691

Spin-orbit coupling (SOC) in graphene can be greatly enhanced by proximity coupling it to transition metal dichalcogenides (TMDs) such as WSe . We find that the strength of the acquired SOC in graphene depends on the stacking order of the heterostructures when using hexagonal boron nitride ( h-BN) as the capping layer, i.e., SiO /graphene/WSe / h-BN exhibiting stronger SOC than SiO /WSe /graphene/ h-BN. We utilize photoluminescence (PL) as an indicator to characterize the interaction between graphene and monolayer WSe grown by chemical vapor deposition. We observe much stronger PL quenching in the SiO /graphene/WSe / h-BN stack than in the SiO /WSe /graphene/ h-BN stack and, correspondingly, a much larger weak antilocalization (WAL) effect or stronger induced SOC in the former than in the latter. We attribute these two effects to the interlayer distance between graphene and WSe , which depends on whether graphene is in immediate contact with h-BN. Our observations and hypothesis are further supported by first-principles calculations, which reveal a clear difference in the interlayer distance between graphene and WSe in these two stacks.