光激发单层膜MoS2带隙重整化的直接测定
Direct Determination of Band Gap Renormalization in Photo-Excited Monolayer MoS2
摘要：
单层半导体，如过渡金属二硫属化物，的一个关键特征是屏蔽库仑势差，这导致大的激子结合能（Eb）和载流子对准粒子带隙（Eg）的强重整化。由于Eb和Eg的变化相互抵消，后者很难确定，导致在不同的载流子密度下，光跃迁能量几乎没有变化。在这里，我们量化的宏观单晶二硫化钼单层SiO2的带隙重整化使用时间和角度分辨光电子能谱（TR-ARPES）。在Mott阈值以上的激发密度，Eg减少多达360毫电子伏。我们比较了载流子密度相关的Eg与以前的理论计算，并显示了在量化的带隙中知道掺杂和激发密度的必要性。
英文摘要：
A key feature of monolayer semiconductors, such as transition-metal dichalcogenides, is the poorly screened Coulomb potential, which leads to large exciton binding energy (Eb) and strong renormalization of the quasiparticle bandgap (Eg) by carriers. The latter has been difficult to determine due to cancellation in changes of Eb and Eg, resulting in little change in optical transition energy at different carrier densities. Here we quantify bandgap renormalization in macroscopic single crystal MoS2 monolayers on SiO2 using time and angle resolved photoemission spectroscopy (TR-ARPES). At excitation density above the Mott threshold, Eg decreases by as much as 360 meV. We compare the carrier density dependent Eg with previous theoretical calculations and show the necessity of knowing both doping and excitation densities in quantifying the bandgap.
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