Predicted bandgap opening in highly-oriented wrinkles formed in chemical vapour deposition grown graphene

We present a combined atomic force microscopy and Raman spectroscopy study of wrinkle formation in chemical vapour deposition graphene. Graphene was grown on copper and repeatedly transferred onto a SiO2 substrate to form a four-layer graphene stack. By means of depositing two electrodes with a small gap of 1 μm on top of graphene, we can generate a long wrinkle along the channel. Such a wrinkle is pronounced and seems to form at the expense of other wrinkles otherwise present. Along the wrinkle, the strain measured by both atomic force microscopy and polarized Raman is revealed to be of a biaxial type, which is shown, through atomistic modelling, is predicted to produce a sizeable bandgap opening of up to 0.4 eV. Since graphene is normally a zero bandgap material, its applications as an electronic material for devices can be limited. The approach presented in this work could lead to graphene exhibiting a controllable bandgap similar to a semiconductor material that could, therefore, be exploited for the fabrication of graphene-based electronic devices.