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

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 × 10 13 cm −2 while providing excellent charge mobility ( μ ~ 25 000 cm 2 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.