Postgrowth modification of monolayer graphene films by low-pressure diborane-argon plasma

Polycrystalline monolayer graphene films grown by chemical vapor deposition were exposed to a low-pressure inductively coupled plasma operated in a gaseous mixture of argon and diborane. Optical emission spectroscopy and plasma sampling mass spectrometry reveal high B2H6 fragmentation leading to significant populations of both boron and hydrogen species in the gas phase. X-ray photoelectron spectroscopy indicates the formation of a boron-containing layer at the surface and provides evidence of a substitutional incorporation of boron atoms within the graphene lattice. Graphene doping by graphitic boration is confirmed by hyperspectral Raman imaging of graphene domains. These results demonstrate that diborane-containing plasmas are efficient tools for boron substitutional incorporation in graphene with minimal domain hydrogenation.