Alkalide-assisted direct electron injection for the noninvasive n-type doping of graphene

Abstract

Although the doping of graphene grown by chemical vapor deposition is important in graphene-based electronics, noninvasive mothods of n-type doping have not been widely investigated in comparison with p type doping methods. We developed a convenient and robust method for the noninvasive n-type doping of graphene, wherein electrons are directly injected from sodium anions into the graphene. This method involves immersing the graphene in solutions of [K(15-crowng-5)2] Na prepared by dissolving NaK alloy in 15-crown-5 soluiton. The n-type doping of grahene was confirmed by down-shifted G and 2D bands in Raman spectra and by the Dirac point shifting to a negative voltage.