Figure 4. Raman and thermal imaging of a covered epitaxial graphene device.

(a) Raman image of 2D-mode peak position before self-heating. Variation in peak position indicative of multilayer boundaries and mobility reductions are evident near left contact. (b) IR measured temperature distribution while dissipating 325 mW of power. (c) Raman image of 2D-mode peak position after failure. (d) Overlay of (b,c) indicating that the failure is co-located with regions of most severe heating. The grounded electrode is on the right-hand side.