Substitutional oxygen activated photoluminescence enhancement in monolayer transition metal dichalcogenides

Atomically thin transition metal dichalcogenides (TMDCs) are intriguing semiconductors for photonics and optoelectronics, and therefore enhancing their photoluminescence (PL) efficiency is crucial for these applications. Many efforts have been contributed to enhancing the PL performance of monolayer TMDCs, yet the complexity between the microstructure and the PL efficiency has hindered the manipulation of their PL properties. Here we demonstrate that the PL intensity of the monolayer TMDC can be enhanced by nearly one order of magnitude with a ∼20% narrower spectral linewidth after a pre-activation plateau using laser irradiation in ambient environment. Combined experimental and theoretical studies reveal that low-power laser irradiation generates many sulfur vacancy clusters, which are subsequently filled up by oxygen, and the lattice substitutional oxygen clusters induce the dramatic PL enhancement of monolayer WS2. Such PL enhancement phenomenon is found to be universal for other monolayer TMDCs, and thus would benefit their versatile optical applications.

具有原子层厚度的过渡金属硫族化合物(TMDCs)是一种适用于 光子和光电子领域的新颖的半导体材料, 而增强其光致发光(PL)特性 对于这类材料的光学应用至关重要. 尽管研究人员做了大量的工作来 增强单层TMDCs的PL特性, 但微观结构和PL效率之间的复杂关系阻碍 了对其性质的调控. 本文中, 我们证实了在激光辐照下, 单层TMDC的 PL强度在经过一个预激活的平台后可以增强近一个数量级且半峰宽变 窄约20%. 实验和理论研究表明, 低功率的激光辐照能够在WS2中产生 许多硫空位簇, 这些硫空位簇随后被氧取代并显著增强其PL. 这种PL增 强的现象在其他单层TMDC材料中有普适性, 有利于TMDC在光学领 域的应用。