A comparison of various surface charge transfer hole doping of graphene grown by chemical vapour deposition

Highlights: • A comparison of the charge transfer doping of graphene using chemical and metal oxide has been demonstrated. • It is possible to increase the carrier concentration by one order which correspond to a decrease in sheet resistance of about 80%. • Rapid thermal annealing is identified to induce p-doping in graphene. • MoO₃ can be considered as a potential material for graphene doping as it can act as a protective coating. • Single layer graphene films with sheet resistance values between 100 and 200 ohm/square have been achieved through two-step growth followed by doping. - Abstract: Charge transfer doping is a renowned route to modify the electrical and electronic properties of graphene. Understanding the stability of potentially important charge-transfer materials for graphene doping is a crucial first step. Here we present a systematic comparison on the doping efficiency and stability of single layer graphene using molybdenum trioxide (MoO₃), gold chloride (AuCl₃), and bis(trifluoromethanesulfonyl)amide (TFSA). Chemical dopants proved to be very effective, but MoO₃ offers better thermal stability and device fabrication compatibility. Single layer graphene films with sheet resistance values between 100 and 200 ohm/square were consistently produced by implementing a two-step growth followed by doping without compromising the optical transmittance.