Qiu Zhizhan, Trushin Maxim, Fang Hanyan, Verzhbitskiy Ivan, Gao Shiyuan, Laksono Evan, Yang Ming, Lyu Pin, Li Jing, Su Jie, Telychko Mykola, Watanabe Kenji, Taniguchi Takashi, Wu Jishan, Neto A H Castro, Yang Li, Eda Goki, Adam Shaffique, Lu Jiong
Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.
NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, 28 Medical Drive, Singapore 117456, Singapore.
Sci Adv. 2019 Jul 19;5(7):eaaw2347. doi: 10.1126/sciadv.aaw2347. eCollection 2019 Jul.
Understanding the remarkable excitonic effects and controlling the exciton binding energies in two-dimensional (2D) semiconductors are crucial in unlocking their full potential for use in future photonic and optoelectronic devices. Here, we demonstrate large excitonic effects and gate-tunable exciton binding energies in single-layer rhenium diselenide (ReSe) on a back-gated graphene device. We used scanning tunneling spectroscopy and differential reflectance spectroscopy to measure the quasiparticle electronic and optical bandgap of single-layer ReSe, respectively, yielding a large exciton binding energy of 520 meV. Further, we achieved continuous tuning of the electronic bandgap and exciton binding energy of monolayer ReSe by hundreds of milli-electron volts through electrostatic gating, attributed to tunable Coulomb interactions arising from the gate-controlled free carriers in graphene. Our findings open a new avenue for controlling the bandgap renormalization and exciton binding energies in 2D semiconductors for a wide range of technological applications.
了解二维（2D）半导体中显著的激子效应并控制激子结合能，对于释放其在未来光子和光电器件中的全部潜力至关重要。在此，我们展示了背栅石墨烯器件上单层二硒化铼（ReSe）中的大激子效应和栅极可调激子结合能。我们分别使用扫描隧道光谱和差分反射光谱来测量单层ReSe的准粒子电子和光学带隙，得到了520毫电子伏特的大激子结合能。此外，我们通过静电栅控实现了单层ReSe的电子带隙和激子结合能连续数百毫电子伏特的调谐，这归因于石墨烯中栅极控制的自由载流子产生的可调库仑相互作用。我们的发现为在二维半导体中控制带隙重整化和激子结合能开辟了一条新途径，可用于广泛的技术应用。
