Raman study on the effects of annealing atmosphere of patterned graphene

Despite extensive research on graphene, there are still lacks of understanding the structural changes under harsh stress environments such as high current in uncontrolled atmosphere. Investigating the structural changes of graphene patterned into device at high temperature would be important as the electrical current path of graphene becomes narrower and thus stronger in heat dissipation. In this paper, we performed a comparative study of the structural and electronical changes of graphene for as-grown graphene and patterned graphene in a microbridge shape heated up to 500 °C in air or Ar. While the as-grown graphene heated in air or Ar was nearly free from the structural changes, the microbridge graphene exhibited strong structural changes after annealing in Ar, i.e. the broadening in the G and the 2D peaks remained even after cooling back to 30 °C. On the other hand, the microbridge graphene heated in air was observed to release stress probably due to formation of vacancies by oxygen adsorption. The different behavior of microbridge graphene heated in Ar from that of as-grown graphene in the same condition is obvious. This means that graphene in microscopic devices should be treated differently from the as-grown graphene.