Interface interactions at insulator/graphene heterostructures

Entani, Shiro; Matsumoto, Yoshihiro; Otomo, Manabu; Avramov, P.; Naramoto, Hiroshi*; Sakai, Seiji

Graphene has attracted much attention as the most promising material for realizing molecular spintronic devices. The understanding of the insulator/graphene interface is of special importance for controlling the spin injection/ejection efficiency. In this work, we studied the interface properties of AlO and SiO/graphene heterostructures by micro-Raman spectroscopy. The changes in the Raman peaks (G and 2D bands) of graphene indicate finite interactions at the insulator/graphene interfaces. In the heterostructure of AlO/graphene, the G and 2D bands are stiffened (up-shifted) compared to pristine graphene. It has been demonstrated that the G peak is stiffened for both electron and hole doping, whereas the 2D peak is softened or stiffened for the respective doping types. Taking account of these relationships, the observed peak shifts of the G and 2D bands are attributed to hole doping in the AlO/graphene heterostructure.