电场调控双层WSe_(2)转角同质结激子莫尔势

Exciton moirépotential in twisted WSe_(2) homobilayers modulated by electric field

二维过渡金属硫化物构成的范德瓦耳斯异质结由于存在晶格失配或层间相对旋转角度会产生周期性的莫尔条纹结构,由此引入的纳米尺度莫尔周期势可以影响激子的空间传输过程.目前有关双层过渡金属硫化物转角同质结中激子莫尔势调控的研究比较有限,本工作利用第一性原理计算研究了外加垂直电场对不同旋转角度的双层WSe_(2)同质结激子莫尔势的影响,发现层间激子莫尔势的大小和势垒/势阱的位置与层间相对旋转角度及电场强度有关,不同旋转角度的双层WSe_(2)同质结激子莫尔势大小及势垒/势阱的位置随电场强度(1 V/nm)的变化不同.这些结果为调控层间激子的局域与非局域转变提供了理论依据和数据预测,在推动人工激子晶体及纳米阵列激光器等半导体器件的发展方面具有重要指导意义.

The nanoscale periodic energy potential is introduced by moiré pattern in two stacked transition metal dichalcogenide monolayers with lattice mismatch or crystal orientation misalignment.It is demonstrated that the moiré potential can act as a diffusion barrier that affects interlayer exciton transport,providing an opportunity for studying the electronic and optical properties of moiréexcitons.However,the current research on the modulation of exciton moiré potential in twisted homobilayers is limited.In this paper the effect of externally applied perpendicular electric field on the exciton moirépotential in twisted WSe_(2) homobilayers with different rotation angles is studied by using first principle calculations.It is found that the amplitude and shape of the interlayer exciton moirépotential are dependent on the relative rotation angle between the layers and electric field intensity.The amplitude and shape of the moirépotential in the twisted WSe_(2) homobilayers with different rotation angles vary with the electric field intensity(1 V/nm).These results provide theoretical basis and data prediction for modulating the local and the non-local transition of interlayer excitons,and are of great significance in promoting the development of semiconductor devices such as artificial excitonic crystals and nanoarray lasers.