Confinement of excited states in two-dimensional, in-plane, quantum heterostructures

Gwangwoo Kim; Benjamin Huet; Christopher E Stevens; Kiyoung Jo; Jeng-Yuan Tsai; Saiphaneendra Bachu; Meghan Leger; Seunguk Song; Mahfujur Rahaman; Kyung Yeol Ma; Nicholas R Glavin; Hyeon Suk Shin; Nasim Alem; Qimin Yan; Joshua R Hendrickson; Joan M Redwing; Deep Jariwala

doi:10.1038/s41467-024-50653-x

Confinement of excited states in two-dimensional, in-plane, quantum heterostructures

Nat Commun. 2024 Jul 28;15(1):6361. doi: 10.1038/s41467-024-50653-x.

Authors

Gwangwoo Kim^{1

2}, Benjamin Huet³, Christopher E Stevens^{4

5}, Kiyoung Jo¹, Jeng-Yuan Tsai⁶, Saiphaneendra Bachu⁷, Meghan Leger⁷, Seunguk Song¹, Mahfujur Rahaman¹, Kyung Yeol Ma⁸, Nicholas R Glavin⁹, Hyeon Suk Shin^{10

11}, Nasim Alem^{3

7}, Qimin Yan⁶, Joshua R Hendrickson⁴, Joan M Redwing^{3

7}, Deep Jariwala¹²

Affiliations

¹ Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, PA, 19104, USA.
² Department of Engineering Chemistry, Chungbuk National University, Cheongju, 28644, Republic of Korea.
³ 2D Crystal Consortium-Materials Innovation Platform, Materials Research Institute, The Pennsylvania State University, University Park, PA, 16802, USA.
⁴ Air Force Research Laboratory, Sensors Directorate, Wright-Patterson Air Force Base, Dayton, OH, 45433, USA.
⁵ KBR Inc, Beavercreek, OH, 45431, USA.
⁶ Department of Physics, Northeastern University, Boston, MA, 02115, USA.
⁷ Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16802, USA.
⁸ Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), UNIST-gil 50, Ulsan, 44919, Republic of Korea.
⁹ Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, Dayton, OH, 45433, USA.
¹⁰ Department of Energy Science and Department of Chemistry, Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea.
¹¹ Center for 2D Quantum Heterostructures, Institute of Basic Science (IBS), Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea.
¹² Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, PA, 19104, USA. [email protected].

Abstract

Two-dimensional (2D) semiconductors are promising candidates for optoelectronic application and quantum information processes due to their inherent out-of-plane 2D confinement. In addition, they offer the possibility of achieving low-dimensional in-plane exciton confinement, similar to zero-dimensional quantum dots, with intriguing optical and electronic properties via strain or composition engineering. However, realizing such laterally confined 2D monolayers and systematically controlling size-dependent optical properties remain significant challenges. Here, we report the observation of lateral confinement of excitons in epitaxially grown in-plane MoSe₂ quantum dots (~15-60 nm wide) inside a continuous matrix of WSe₂ monolayer film via a sequential epitaxial growth process. Various optical spectroscopy techniques reveal the size-dependent exciton confinement in the MoSe₂ monolayer quantum dots with exciton blue shift (12-40 meV) at a low temperature as compared to continuous monolayer MoSe₂. Finally, single-photon emission (g²(0) ~ 0.4) was also observed from the smallest dots at 1.6 K. Our study opens the door to compositionally engineered, tunable, in-plane quantum light sources in 2D semiconductors.

Grants and funding

FA2386-20-1-4074/United States Department of Defense | United States Air Force | AFMC | Air Force Office of Scientific Research (AF Office of Scientific Research)