Strain-enabled polarity reversal of transport in Bi/MoS2 van der Waals heterostructures

Abstract

Strain engineering serves as a powerful strategy for modulating the electronic properties of semiconductors and enhancing device performance. In this work, we employ first-principles calculations to systematically explore the mechanical properties, electronic structure, and charge carrier mobility of a bismuth/molybdenum disulfide (Bi/MoS2) van der Waals heterostructure under applied strain. The heterostructure demonstrates notable mechanical robustness and pronounced anisotropy. For the AB1 stacking configuration, the electron mobility reaches 1.51 × 105 and 1.56 × 105 cm2 V−1 s−1 along the x- and y-directions, respectively, while the hole mobility is 4.54 × 104 and 1.65 × 103 cm2 V−1 s−1—one to two orders of magnitude lower than that of electrons. Remarkably, under a 2% strain, the electron mobility attains 6.5 × 104 and 2.94 × 104 cm2 V−1 s−1, whereas the hole mobility rises significantly to 2.66 × 106 and 7.34 × 105 cm2 V−1 s−1. This results in a striking polarity reversal, with hole mobility surpassing that of electrons by one to two orders of magnitude. Our findings reveal that strain not only effectively tunes the electronic structure but also induces a switch in the dominant charge carrier type—from electrons to holes—under specific strain conditions. These insights provide critical theoretical guidance for the design of strain-modulated electronic devices based on Bi/MoS2 heterostructures.