Mechanical strain and electric-field modulation of graphene transistors integrated on MEMS cantilevers

Abstract

This work proposes a structure which allows characterization of graphene monolayers under combined electric field and mechanical strain modulation. Our approach is based on a cantilever integrated into a two-dimensional graphene-based field effect transistor (FET). This allows us to change graphene properties either separately or together via two methods. The first way involves electric field induced by the gate. The second is induction of mechanical strain caused by external force pushing the cantilever up or down. We fabricated devices using silicon-on-insulator wafer with practically zero value of residual stress and a high-quality dielectric layer which allowed us to precisely characterize structures using both mentioned stimuli. We used the electric field/strain interplay to control resistivity and position of the charge neutrality point often described as the Dirac point of graphene. Furthermore, values of mechanical stress can be obtained during the preparation of thin films, which enables the cantilever to bend after the structure is released. Our device demonstrates a novel method of tuning the physical properties of graphene in silicon and/or complementary metal-oxide-semiconductor technology, and is thus promising for tunable physical or chemical sensors.

Strain engineering of graphene on rigid substrates

“…As shown in the previous literature, formvar resin as a protective layer can supply graphene with an effective support during the transfer process. 30 As shown by the comparative experimental result without formvar in Fig. 4b , the obtained graphene on the SiO 2 /Si substrate is destroyed disastrously.…”