Department of Physics, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea.
KU Photonics Center, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea.
Nano Lett. 2023 May 24;23(10):4282-4289. doi: 10.1021/acs.nanolett.3c00460. Epub 2023 May 11.
Excitons, electron-hole pairs in semiconductors, can be utilized as information carriers with a spin or valley degree of freedom. However, manipulation of excitons' motion is challenging because of their charge-neutral characteristic and short recombination lifetimes. Here we demonstrate electric-field-driven drift and funneling of charged excitons (i.e., trions) toward the center of a MoSe monolayer. Using a simple bottom-gate device, we control the electric fields in the vicinity of the suspended monolayer, which increases the trion density and pulls down the layer. We observe that locally excited trions are subjected to electric force and, consequently, drift toward the center of the stretched layer. The exerting electric force on the trion is estimated to be 10-10 times stronger than the strain-induced force in the stretched monolayer, leading to the successful observation of trion drift under continuous-wave excitation. Our findings provide a new route for manipulating trions and achieving new types of optoelectronic devices.
激子，半导体中的电子-空穴对，可以作为具有自旋或谷自由度的信息载体。然而，由于其电荷中性的特性和短的复合寿命，激子的运动操纵具有挑战性。在这里，我们演示了电场驱动的带电激子（即三电子空穴）向 MoSe 单层中心的漂移和汇聚。使用简单的底栅器件，我们控制了悬浮单层附近的电场，这增加了三电子空穴的密度并下拉了该层。我们观察到局部激发的三电子空穴受到电场力的作用，因此向拉伸层的中心漂移。施加在三电子空穴上的电场力估计比拉伸单层中应变诱导的力强 10-10 倍，从而在连续波激发下成功观察到三电子空穴的漂移。我们的发现为操纵三电子空穴和实现新型光电设备提供了新途径。
