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Spontaneous doping on high quality talc-graphene-hBN van der Waals heterostructures

2017; IOP Publishing; Volume: 4; Issue: 3 Linguagem: Inglês

10.1088/2053-1583/aa76f4

2053-1583

Edrian Mania, Ananias B Alencar, Alisson R. Cadore, Bruno R. Carvalho, Kenji Watanabe, Takashi Taniguchi, Bernardo R. A. Neves, H. Chacham, Leonardo C. Campos,

2D Materials and Applications

Steady doping, added to its remarkable electronic properties, would make graphene a valuable commodity in the solar cell market, as energy power conversion could be substantially increased. Here we report a graphene van der Waals heterostructure which is able to spontaneously dope graphene (p-type) up to n ~ 2.2 × 1013 cm−2 while providing excellent charge mobility ( ~ 25 000 cm2 V−1 s−1). Such properties are achieved via deposition of graphene on atomically flat layered talc, a natural and abundant dielectric crystal. Raman investigation shows a preferential charge accumulation on graphene-talc van der Waals heterostructures, which are investigated through the electronic properties of talc/graphene/hBN heterostructure devices. These heterostructures preserve graphene's good electronic quality, verified by the observation of quantum Hall effect at low magnetic fields (B = 0.4 T) at T = 4.2 K. In order to investigate the physical mechanisms behind graphene-on-talc p-type doping, we performed first-principles calculations of their interface structural and electronic properties. In addition to potentially improving solar cell efficiency, graphene doping via van der Waals stacking is also a promising route towards controlling the band gap opening in bilayer graphene, promoting a steady n or p type doping in graphene and, eventually, providing a new path to access superconducting states in graphene, predicted to exist only at very high doping.