Impact of Strain in Free-Standing PtSe₂ in Scalable 2D MEMS.

Abstract

2D layered materials such as PtSe₂ are prime candidates for next-generation micro- and nano-electro-mechanical systems (MEMS/NEMS), including piezoresistive sensors. However, due to difficulties in large-scale synthesis and the inherent drawbacks associated with mechanical transfer of 2D material films, scalable NEMS production remains challenging. In this work, we report a fabrication route for free-standing, as-grown 2D material channels of PtSe₂ with controlled dimensions, avoiding a mechanical film transfer. The free-standing devices provide a universal platform for strain engineering of 2D materials because tension can be easily controlled by application of a back-contact voltage. Moreover, the piezoresistivity of PtSe₂, together with the possibility of wafer-scale synthesis at back-end-of-line compatible growth temperatures, make it ideally suited for scalable incorporation into integrated circuits. Our measurements show that the material properties can be tuned via strain, which offers pathways for classically non-gateable materials in electronic and photonic devices. Finite element simulations of representative free-standing films elucidate the nano-mechanical properties of large-scale-grown, polycrystalline 2D materials under tensile strain and demonstrate the influence of polycrystallinity on the optical and electrical behavior.