Strain-enabled defect migration and defect activation in monolayer MoS2

Abstract

Two-dimensional (2D) materials possess remarkable strain tolerance and exhibit strain-tunable properties, making them highly promising for flexible device applications. Defects within these materials significantly impact their optoelectronic response to strain. In this study, we investigate the influence of strain on the electrical properties of monolayer MoS2, emphasizing the pivotal role played by intrinsic defects in shaping the material's electrical and optoelectronic response under strain. We observed an enhancement in photocurrent and persistent photoconductivity at specific strains, indicating the activation of defects at these strain values, thus enhancing the photoresponse. Moreover, our device exhibits diodic behavior at specific strain values after prolonged measurements under a static field, suggesting a reduction in the migration energy of defects caused by the applied strain. This finding holds significant implications for memory, logic, and flexible devices. Additionally, we observe an increase in electron mobility under tensile strain, with our flexible field-effect transistor exhibiting higher mobility (∼38 cm2 (V·s)−1) at 0.4% strain. Our study provides insight into the role of strain in the activation and migration of defects in monolayer MoS2 and opens up new avenues for the development of multifunctional ultra-thin flexible devices and memory applications.