Establishment of a reliable transfer process for fabricating chemical vapor deposition-grown graphene films with advanced and repeatable electrical properties.

Graphene films grown by the chemical vapor deposition (CVD) method have attracted intensive attention due to their native advantages of both high quality and large quantity for commercial applications. However, previously reported graphene films have exhibited uncertain and conflicted electrical properties that greatly hinder them from being used to build reliable electrical devices because of incompatibility during the complex and multifarious transfer process. Herein, the relationship between the transfer parameters and electrical performance was systematically studied. It demonstrates that cracking during the transfer process causes significant loss of carrier mobility and hence an increase in sheet resistance. Additionally, unstable doping plays a key role in the carrier density and hence greatly influences the sheet resistance. By introducing HCl as a doping agent, graphene films with repeated sheet resistance of approximately 300 ohm sq can be realized. This work establishes a facile and reliable route to fabricate graphene films with advanced and repeatable electrical properties, which is significant and essential for fair evaluation of CVD-grown graphene films and further practical applications.