Multifunctional van der Waals heterostructures enabled by femtosecond laser-controlled band alignment engineering

Abstract

Tailoring the band alignment of van der Waals (vdW) heterostructures is essential for regulating the electronic and optoelectronic performance of devices with superior functions. However, current band alignment engineering methods suffer from complexity, inflexibility, and limited tuning range, which hinders further applications. In this study, we demonstrate a novel strategy for tailoring the band alignment of BP/MoS2 heterostructures using femtosecond (fs) laser-controlled band alignment engineering. Although this approach compromises the rectification ratio of heterostructures, it dramatically expands the tuning range of the band alignment and improves optoelectronic response by localized doping and healing effect at heterojunctions. We also present a new physical model to describe carrier transport behavior for m-n-p structures and investigate the effect of fs laser irradiation. Finally, two conceptual devices are demonstrated to show the advanced applications of this post-processing technique. In optoelectronic applications, we utilized this strategy to improve photoresponsivity (> 8 times), detectivity (∼1.48 ×1011 Jones), and fill the response gap in the NIR region of photodetectors. In multivalued logic applications, site-specific engineering was used to transform the inverter operating mode from binary to ternary with a wide output swing (∼90%) by creating a unique NDT region. Our study demonstrates the potential of fs laser irradiation as a high-spatial-accuracy, air-stable, and versatile band alignment engineering method for electronic and optoelectronic applications in the future.