Improving the photoresponse performance of monolayer MoS₂ photodetector via local flexoelectric effect

Abstract

Strain engineering is an effective means of modulating the optical and electrical properties of two-dimensional (2D) materials. The flexoelectric effect caused by inhomogeneous strain exists in most dielectric materials, which breaks the limit of the materials’ non-centrosymmetric structure for piezoelectric effect. However, there is a lack of understanding of the impact on optoelectronic behaviour of monolayer MoS2 photodetector via local flexoelectric effect triggered by biaxial strain. In this paper, we develop a probe tip (Pt)–MoS2-Au asymmetric Schottky barrier photodetector based on conductive atomic force microscopy (CAFM) to investigate the impact of flexoelectric effect on the photoresponse performance. Consequently, when the probe force increases from 24 nN to 720 nN, the photocurrent, responsivity and detectivity increase 28.5 times, 29.6 times and 5.3 times at forward bias under 365 nm light illumination, respectively. These results indicate that local flexoelectric effect plays a critical role to improve the photoresponse performance of photodetector. Our approach suggests a new route to improve the performance of photodetectors by introducing local flexoelectric polarization field, offering the potential for the application of strain modulated photoelectric devices.

Tuning electronic and optical properties of monolayer MoS2 by transition metal and nitrogen co-doping

“…Ultra-broadband response photodetectors that can cover the IR region will show great application prospects in the fields of fluorescence imaging, biomedicine, environmental monitoring, and remote sensing [1][2][3]. In recent years, transition metal dichalcogenides, such as MoS 2 , have been considered as a possible candidate for a new generation of broadband photodetectors due to their unique structures and electronic properties [4][5][6][7]. However, the optical absorption range of MoS 2 is limited to the ultraviolet to visible (UV−VL) region due to its relatively large band gap [5,8,9].…”