Kim Gwangwoo, Huet Benjamin, Stevens Christopher E, Jo Kiyoung, Tsai Jeng-Yuan, Bachu Saiphaneendra, Leger Meghan, Song Seunguk, Rahaman Mahfujur, Ma Kyung Yeol, Glavin Nicholas R, Shin Hyeon Suk, Alem Nasim, Yan Qimin, Hendrickson Joshua R, Redwing Joan M, Jariwala Deep
Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, PA, 19104, USA.
Department of Engineering Chemistry, Chungbuk National University, Cheongju, 28644, Republic of Korea.
Nat Commun. 2024 Jul 28;15(1):6361. doi: 10.1038/s41467-024-50653-x.
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 quantum dots (~15-60 nm wide) inside a continuous matrix of WSe monolayer film via a sequential epitaxial growth process. Various optical spectroscopy techniques reveal the size-dependent exciton confinement in the MoSe monolayer quantum dots with exciton blue shift (12-40 meV) at a low temperature as compared to continuous monolayer MoSe. Finally, single-photon emission (g(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.
二维（2D）半导体因其固有的面外二维限制，是光电子应用和量子信息处理的有前途的候选材料。此外，它们还提供了实现低维面内激子限制的可能性，类似于零维量子点，通过应变或成分工程具有引人入胜的光学和电子特性。然而，实现这种横向受限的二维单层并系统地控制尺寸依赖的光学特性仍然是重大挑战。在此，我们报告了通过连续外延生长过程，在WSe单层膜的连续基质内，观察到外延生长的面内MoSe量子点（宽度约15 - 60纳米）中激子的横向限制。各种光谱技术揭示了MoSe单层量子点中尺寸依赖的激子限制，与连续单层MoSe相比，低温下激子发生蓝移（12 - 40毫电子伏特）。最后，在1.6 K下，从最小的量子点中还观察到了单光子发射（g(0)约为0.4）。我们的研究为二维半导体中成分工程化、可调谐的面内量子光源打开了大门。
