Theoretical study on the top- and enclosed-contacted single-layer MoS₂ piezotronic transistors

Recently, the piezotronic effect has been observed in two-dimensional single-layer MoS₂ materials, which have potential applications in force and pressure triggered or controlled electronic devices, sensors, and human-machine interfaces. However, classical theory faces the difficulty in explaining the mechanism of the piezotronic effect for the top- and enclosed-contacted MoS₂ transistors, since the piezoelectric charges are assumed to exist only at the edge of the MoS₂ flake that is far from the electronic transport pathway. In the present study, we identify the piezoelectric charges at the MoS₂/metal-MoS₂ interface by employing both the density functional theory and finite element method simulations. This interface is on the transport pathway of both top- and enclosed-contacted MoS₂ transistors, thus it is capable of controlling their transport properties. This study deepens the understanding of piezotronic effect and provides guidance for the design of two-dimensional piezotronic devices.