单层 WS_{2}中的激发态电子空穴对

Excited-State Trions in Monolayer WS_{2}.

机构信息

Institute of Physics and Center for Nanotechnology, University of Münster, Wilhelm-Klemm-Straße 10, 48149 Münster, Germany.

Institute of Solid State Theory, Wilhelm-Klemm-Straße 10, University of Münster, 48149 Münster, Germany.

出版信息

Phys Rev Lett. 2019 Oct 18;123(16):167401. doi: 10.1103/PhysRevLett.123.167401.

DOI:10.1103/PhysRevLett.123.167401

PMID:31702327

Abstract

We discover an excited bound three-particle state, the 2s trion, appearing energetically below the 2s exciton in monolayer WS_{2}, using absorption spectroscopy and ab initio GW and Bethe-Salpeter equation calculations. The measured binding energy of the 2s trion (22 meV) is smaller compared to the 1s intravalley and intervalley trions (37 and 31 meV). With increasing temperature, the 1s and 2s trions transfer their oscillator strengths to the respective neutral excitons, establishing an optical fingerprint of trion-exciton resonance pairs. Our discovery underlines the importance of trions for the entire excitation spectrum of two-dimensional semiconductors.

摘要

我们通过吸收光谱和第一性原理 GW 和 Bethe-Salpeter 方程计算发现，在单层 WS_{2}中，激子束缚的三体态 2s 三重子出现在能量上低于 2s 激子的位置。所测量的 2s 三重子（22meV）的结合能比 1s 谷内和谷间三重子（37 和 31meV）小。随着温度的升高，1s 和 2s 三重子将其振子强度转移到相应的中性激子，建立了三重子-激子共振对的光学指纹。我们的发现强调了三重子对二维半导体整个激发谱的重要性。