顕微ラマン分光法を用いたグラフェンのひずみ成分測定

抄録

Graphene is the two-dimensional carbon allotrope. Graphene has a lot of remarkable properties which are useful for mechanical and electronic properties. Therefore, the application of graphene is expected in various fields. However, there are not useful methods to measure strain components in graphene. In this study, crystallographic orientations and strain measurements in single-layered graphene are conducted by polarized Raman microspectroscopy. Graphene has A_1g and doubly degenerate E_2g Raman active vibration modes. The changes of Raman intensities of each Raman line with polarization angle of irradiation laser are theoretically derived and the theoretical changes show good agreement with experimental results. Four point bending tests of graphene on cupper or silicon substrates are conducted. Under the strong bending strain, the doubly degenerate E_2g vibration mode splits in two modes, and the distance between these spitted peaks increases with increasing the applied strain. In A_1g an E_2g modes, the relationships between Raman shift and applied strain indicate the linearity with different slopes. Therefore, applicability of polarized Raman micro spectroscopy to strain measurements is confirmed.