Interface engineering and force tuning electrical transport behaviour of nano-devices based on atomic layered MoS2

Junjie Qi; Feng Li

doi:10.21767/2472-1123-C6-018

Interface engineering and force tuning electrical transport behaviour of nano-devices based on atomic layered MoS2

Euroscicon Conference on Physical Chemistry and Analytical Separation Techniques
October 08-09, 2018 Amsterdam, Netherlands

Junjie Qi and Feng Li

University of Science and Technology Beijing, Peoples Republic of China

Posters & Accepted Abstracts: J Org Inorg Chem

DOI: 10.21767/2472-1123-C6-018

Abstract

High-performance piezoelectricity in monolayer semiconducting transition metal dichalcogenides is highly desirable for the development of nanosensors, piezotronics and photopiezotransistors. Here, we report the experimental study of the theoretically predicted piezoelectric effect in triangle monolayer MoS2 devices under isotropic mechanical deformation. The experimental observation indicates that the conductivity of MoS2 devices can be actively modulated by the piezoelectric charge polarization-induced built-in electric field under strain variation. These polarization charges alter the Schottky barrier height on both contacts resulting in a barrier height increase with increasing compressive strain and decrease with increasing tensile strain. The underlying mechanism of strain-induced in-plane charge polarization is proposed and discussed using energy band diagrams. In addition, a new type of MoS2 strain/force sensor built using a monolayer MoS2 triangle is also demonstrated. Our results provide evidence for strain-gating monolayer MoS2 piezotronics, a promising avenue for achieving augmented functionalities in next-generation electronic and mechanical-electronic nanodevices. Developing nanoelectronics that utilize the vertical subnanometer thickness of two-dimensional materials is desirable for achieving miniaturization of circuit elements. However, only a few researches have been studied in the vertical transport of atomic layered materials so far. Here, the vertical electrical transport behaviour of bilayer MoS2 under coupling of photons and force is explored by the use of conductive atomic force microscopy. We found that the current-voltage behaviour across the tip-MoS2-Pt junction is a tunnelling current which can be well fitted by a Simmons approximation. Among which, direct tunneling is dominated at low bias voltages whereas Fowler-Nordheim tunneling is happened at high bias voltages. The bias voltages in transition point between direct and Fowler-Nordheim tunneling are matched with the tunnelling barrier height of energy band shape difference. Furthermore, the source-drain current dropping surprisingly appears when we continually increase force in which the dropping point is altered by light provided. The potential mechanism is responsible for the tuning in tunnelling barrier height and width by force and photons. These results provide a new way to design devices that takes advantage of ultrathin two-dimensional materials. Such ultra-short channel length electronic components that possess tunnelling current are important for establishing high-efficiency electronic and optoelectronic systems.