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, Nicholas R. Glavin, Hyeon Suk Shin, Nasim Alem, Qimin Yan, Joshua R. Hendrickson, Joan M. Redwing, Deep Jariwala
Abstract
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 MoSe 2 quantum dots (~15-60 nm wide) inside a continuous matrix of WSe 2 monolayer film via a sequential epitaxial growth process. Various optical spectroscopy techniques reveal the size-dependent exciton confinement in the MoSe 2 monolayer quantum dots with exciton blue shift (12-40 meV) at a low temperature as compared to continuous monolayer MoSe 2 . Finally, single-photon emission (g 2 (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.