Nonvolatile Electric Control of Exciton Complexes in Monolayer MoSe2 with Two-Dimensional Ferroelectric CuInP2S6.

ABSTRACT

Monolayer transition-metal dichalcogenides (TMDs) have provided a platform to investigate the excitonic states at the two-dimensional (2D) limit. The inherent properties of excitons in TMDs, such as the photoluminescence quantum yield, the charge states, and even the binding energy, can be effectively controlled via electrostatic gating, selective carrier doping, or substrate dielectric engineering. Here, aiming for the nonvolatile electrical tunability of excitonic states and thereby the optical property of TMDs, we demonstrate a 2D ferroelectric heterostructure with monolayer MoSe2 and ultrathin CuInP2S6 (CIPS). In the heterostructure, the electric polarization of CIPS results in continuous, global, and large electronic modulation in monolayer MoSe2. With the saturated ferroelectric polarization of CIPS, electron-doped or hole-doped MoSe2 is realized in a single device. The carrier density tunability in the heterostructure is as high as 5 × 1012 cm-2. The nonvolatile behavior of these devices up to 3 months is also characterized. Our results provide a new and practical strategy for low-power consumption and agelong tunable optoelectronic devices.