  A method for inducing nonuniform strain in graphene films is developed.
Pillars made of a dielectric material (electron beam resist) are placed between
graphene and the substrate, and graphene sections between pillars are attached
to the substrate. The strength and spatial pattern of the strain can be
controlled by the size and separation of the pillars. Application of strain is
confirmed by Raman spectroscopy as well as from scanning electron microscopy
(SEM) images. From SEM images, the maximum stretch of the graphene film reaches
about 20%. This technique can be applied to the formation of band gaps in
graphene.
