Asymmetric bias-tunable surface adhesion of semiconductor nanofilms

Electrically tunable surface adhesion is of vital importance for ubiquitous microelectromechanical systems, and is normally symmetric to the applied bias voltage. Here we report the asymmetric bias-tunable surface adhesion of semiconductor nanofilms by taking molybdenum disulfide (MoS 2 ) as a demo with graphene, hexagonal boron nitride, and bulk n-type doped silicon serving as the normal control group. The bias-tunable adhesion force between the Au-coated tip and the Au back electrode supported MoS 2 nanofilms was deciphered by combining conductive atomic force microscopic examinations in vacuum and theoretical simulations. The asymmetric bias-tunability is found to be significantly stronger than that of the control group, attributing to the built-in electric field at the Schottky junction between the nanofilm and back electrode.