Abstract
Understanding the mechanism and limits of strain transfer between
supported 2D systems and their substrate is a most needed step toward
the development of strain engineering at the nanoscale. This includes
applications in straintronics, nanoelectromechanical devices, or new
nanocomposites. Here, we have studied the limits of biaxial compressive
strain transfer among SiO2, diamond, and sapphire substrates and
graphene. Using high pressure-which allows maximizing the adhesion
between graphene and the substrate on which it is deposited we show that
the relevant parameter governing the graphene mechanical response is not
the applied pressure but rather the strain that is transmitted from the
substrate.. Under these experimental conditions, we also show the
existence of a critical biaxial stress beyond which strain transfer
become partial and introduce a parameter, a, to characterize strain
transfer efficiency. The critical stress and a appear to be dependent on
the nature of the substrate. Under ideal biaxial strain transfer
conditions, the phonon Raman G-band dependence with strain appears to be
linear with a slope of -60 +/- 3 cm(-1)/% down to biaxial strains of
-0.9%. This evolution appears to be general for both biaxial
compression and tension for different experimental setups, at least in
the biaxial strain range -0.9% epsilon < 1.8%, thus providing a
criterion to validate total biaxial strain transfer hypotheses. These
results invite us to cast a new look at mechanical strain experiments,on
deposited graphene as well as to other 2D layered materials.
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