论文标题
二维钙钛矿/单层WS2异质结构中激子对比度操纵的激子状态的有效电气切换
Efficient electrical switching of exciton states for valley contrast manipulation in two-dimensional perovskite/monolayer WS2 heterostructures
论文作者
论文摘要
过渡金属二甲植物（TMDS）中的耦合自旋谷物理学赋予了山谷自由度的激子状态，这使它们有望在TMDS单层和/或其异质结构中对谷化的应用。尽管已经研究了内层和层间激子（IX）的山谷动力学，但通过切换激子状态对山谷伪杀物进行有效操纵仍然难以捉摸。因此，有效调整激子状态以获取用于山谷编码的实用山谷极化开关非常重要。在这里，我们证明了激子发射的电气转换，其在单层WS2的异质结构和二维（2D）钙钛矿的异质结构中介导的高度可变谷地极化，与旋转和翻译平移无关。通过光致发光激发（PLE）和光致发光（PL）研究来鉴定IX的形成，可以根据单层WS2的静电掺杂水平从正电荷到负电荷进行电动调整。重要的是，我们证明了从二型变为一型带对齐的电气切换，这表现为PL轮廓从CIX到带电的Intralayer Intralayer激子发射的变化。这种过渡引起了两个激子状态之间的山谷极化的较大对比，从而使可逆的电调节谷化开关的最大开/关比为15.8。我们的研究提供了一种替代机制，可以极为简单地实现山谷两极分化的转换，以及对激子物种的电气控制以及相关的山谷 - 对抗物理，将进一步促进光电和valleytronic设备的开发
The coupled spin-valley physics in transition metal dichalcogenides (TMDs) endows exciton states with valley degrees of freedom, making them promising for valleytronic applications in TMDs monolayers and/or their heterostructures. Although the valley dynamics of intralayer and interlayer excitons (IXs) have been studied, efficient manipulation of valley pseudospins by switching exciton states remains elusive. Therefore, it is of great importance to effectively tune the exciton states to obtain practical valley polarization switches for valley encoding. Here, we demonstrate the electrical switching of exciton emission with highly variable valley polarization mediated by charged IXs (CIXs) in the heterostructure of monolayer WS2 and two-dimensional (2D) perovskite, irrespective of lattice constants, the rotational and translational alignment. The formation of IXs is identified by photoluminescence excitation (PLE) and photoluminescence (PL) studies, which can be further electrically tuned from positively charged to negatively charged depending on the electrostatic doping level of monolayer WS2. Importantly, we demonstrate an electrical switching from type two to type one band alignment, manifesting as a change in the PL profile from CIX to charged intralayer exciton emission. Such transition induces a large contrast in valley polarization between the two exciton states, enabling the reversible electrically regulated valley polarization switch with a maximum ON/OFF ratio of 15.8. Our study provides an alternative mechanism to achieve valley polarization switching with great simplicity for valleytronics and the electrical control of exciton species and associated valley-contrasting physics would further facilitate the development of optoelectronic and valleytronic devices
