Kesarwani Rahul, Simbulan Kristan Bryan, Huang Teng-De, Chiang Yu-Fan, Yeh Nai-Chang, Lan Yann-Wen, Lu Ting-Hua
Department of Physics, National Taiwan Normal University, Taipei, Taiwan.
Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA.
Sci Adv. 2022 Apr;8(13):eabm0100. doi: 10.1126/sciadv.abm0100. Epub 2022 Apr 1.
Controlling the density of exciton and trion quasiparticles in monolayer two-dimensional (2D) materials at room temperature by nondestructive techniques is highly desired for the development of future optoelectronic devices. Here, the effects of different orbital angular momentum (OAM) lights on monolayer tungsten disulfide at both room temperature and low temperatures are investigated, which reveal simultaneously enhanced exciton intensity and suppressed trion intensity in the photoluminescence spectra with increasing topological charge of the OAM light. In addition, the trion-to-exciton conversion efficiency is found to increase rapidly with the OAM light at low laser power and decrease with increasing power. Moreover, the trion binding energy and the concentration of unbound electrons are estimated, which shed light on how these quantities depend on OAM. A phenomenological model is proposed to account for the experimental data. These findings pave a way toward manipulating the exciton emission in 2D materials with OAM light for optoelectronic applications.
对于未来光电器件的发展而言，非常希望能够通过无损技术在室温下控制单层二维（2D）材料中激子和三重子准粒子的密度。在此，研究了不同轨道角动量（OAM）光在室温和低温下对单层二硫化钨的影响，结果表明，随着OAM光拓扑电荷的增加，光致发光光谱中的激子强度同时增强，三重子强度受到抑制。此外，发现三重子到激子的转换效率在低激光功率下随OAM光迅速增加，而随功率增加而降低。此外，还估算了三重子结合能和未束缚电子的浓度，这揭示了这些量如何依赖于OAM。提出了一个唯象模型来解释实验数据。这些发现为利用OAM光操纵二维材料中的激子发射以用于光电子应用铺平了道路。
