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 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.
@article{arxiv.2307.06404,
title = {Exciton Confinement in Two-Dimensional, In-Plane, Quantum Heterostructures},
author = {Gwangwoo Kim and Benjamin Huet and Christopher E. Stevens and Kiyoung Jo and Jeng-Yuan Tsai and Saiphaneendra Bachu and Meghan Leger and Kyung Yeol Ma and Nicholas R. Glavin and Hyeon Suk Shin and Nasim Alem and Qimin Yan and Joshua R. Hedrickson and Joan M. Redwing and Deep Jariwala},
journal= {arXiv preprint arXiv:2307.06404},
year = {2023}
}