Ultrafine Pt nanoparticle induced doping/strain of single layer graphene: experimental corroboration between conduction and Raman characteristics

Abstract

The doping/strain induced by ultrafine sputtered Pt nanoparticles (NPs) of different sizes on single layer graphene is studied through conduction channel modification of graphene-based field-effect transistors and subsequent Raman characterization. For sub-nm (0.5 nm) sized Pt NPs, a substantial Dirac point shift is observed in the I–V characteristics, suggestive of n-type doping of the large area single layer graphene through the process of charge transfer and chemical interaction. Conversely, for larger (1.1 nm) Pt NPs, minimal Dirac point shift is observed, indicating lack of the charge transfer induced doping effect. The representative Raman signatures corroborate with the electrical characterization results and indicate while charge transfer dominates Raman peak shift for the 0.5 nm Pt NP decorated graphene, strain effect dominates in case of the larger 1.1 nm Pt NP.