Reduction of water-molecule-induced current-voltage hysteresis in graphene field effect transistor with semi-dry transfer using flexible supporter

Abstract

The polymethyl methacrylate-assisted wet transfer method of chemical vapor deposition (CVD) graphene has been widely used, thanks to its good coverage and simplicity. However, in the wet-transfer method, water molecules are inevitably trapped between the graphene and the substrate because the graphene is transferred to the substrate while floating in water. The trapped water molecules can cause the unwanted doping of graphene and hysteretic behavior in the current-voltage (I-V) curve. We here propose a new semidry transfer method using the Kapton tape as an additional flexible supporting layer. The N2 blowing and heating processes are added to vaporize the water molecules adsorbed on graphene layer right before the transfer step. By comparing the I-V characteristics of wet- and semidry-transferred graphene field effect transistor (GFET), the field effect mobility is found to be larger for the semidry-transferred GFET in comparison with the wet-transferred one, possibly due to the more uniform Coulomb potential landscape. Most importantly, the hysteretic behavior is found to be reduced in accordance with the decrease of the trapped water molecules. The averaged electron mobilities obtained from the GFET measurements are 1118 c m 2 / V s and 415 c m 2 / V s for semidry- and wet-transferred graphene, respectively. Our semidry transfer method can provide a simple and reliable way to transfer the CVD graphene onto an arbitrary substrate with the minimized number of trapped water molecules, which is readily applicable for large-scale substrates with potential of commercialization.