论文标题
带负质量电子的明亮激子
Bright excitons with negative-mass electrons
论文作者
论文摘要
通常不期望结合的电子孔激发态态以负有效质量的电荷形成。我们在半导体WSE2的单层中识别此类激子，在紫外线中它们会产生狭窄的波段上转向的光致发光，在第一个带边缘的激子转变高于第一个带边缘的能量。负条带曲率和强电子偶联导致级联的声子进展，并在光致发光光谱中与等距峰，可分辨到第九阶。从头开始，具有完整电子孔相关性的GW-BSE计算揭示了上层传导带状态的混合，以与这种复杂的多体激发：一种与半导体连续体共鸣的光学明亮，绑定的激子。该激子负责原子样量子干扰现象，例如电磁诱导的透明度。由于可以通过压力或应变来调节带曲率，因此可行的外来准粒子（例如无限质量质量的平坦频段激子）的合成变得可行。
Bound electron-hole excitonic states are generally not expected to form with charges of negative effective mass. We identify such excitons in a single layer of the semiconductor WSe2, where they give rise to narrow-band upconverted photoluminescence in the UV, at an energy of 1.66 eV above the first band-edge excitonic transition. Negative band curvature and strong electron-phonon coupling result in a cascaded phonon progression with equidistant peaks in the photoluminescence spectrum, resolvable to ninth order. Ab initio GW-BSE calculations with full electron-hole correlations unmask and explain the admixture of upper conduction-band states to this complex many-body excitation: an optically bright, bound exciton in resonance with the semiconductor continuum. This exciton is responsible for atomic-like quantum-interference phenomena such as electromagnetically induced transparency. Since band curvature can be tuned by pressure or strain, synthesis of exotic quasiparticles such as flat-band excitons with infinite reduced mass becomes feasible.
