Scanning tunneling microscope study of striated carbon ridges in few-layer epitaxial graphene formed on 4H-SiC(000-1)

Scanning tunneling microscopy (STM) is used to study carbon ridge defects found in few-layer graphene formed on the C-face of 4H-SiC(000-1) at growth temperatures between 1475\r{ }C and 1550\r{ }C. STM images reveal that ridges are characterized by a striated exterior surface formed from out-of-plane distortions in the hexagonal graphene lattice. While ridge formation is likely explained by compressive in-plane stresses and small values of the bending modulus for few-layer graphene, the striated structure along the ridges argues for a localized unidirectional stress in the material directed along the ridge length.