Towards reproducible graphene synthesis on optimized copper substrates

Abstract

As more knowledge is accumulated in the synthesis of 2D materials, such as graphene, graphene analogues, and transition metal dichalcogenides (TMDs), we are confronted with widely varying qualities of materials synthesized. In order to integrate into current VLSI technology and beyond to wearable technologies, the synthesis of the materials needs to be facile and provide reproducible quality. In order for reproducible graphene to be made, we must have a better understanding of the mechanism that causes the differences in quality of graphene synthesized. Different groups report graphene mobilities with larges variance. Even within the same research group there can be differences in graphene quality from piece to piece. To further graphene research, the quality should be close to the level that we would expect less than a 10% difference from batch to batch or group to group. We examine graphene grown on copper of varying purities. Commercially available copper was chosen to be able to have this work be easily replicated. Additionally, we produced copper film using E-beam evaporation, which is a commonly used method. Graphene was synthesized using methods that have already been outlined in literature to examine the role of the substrate. To enable a transition to flexible substrates for wearable devices, we investigate the use of polymer electrets to provide electrostatic doping to graphene. The benefit of using polymer electrets is that they are solution processable and have well understood properties. These properties hold promise for developing wearable graphene devices. The properties of electrets can be further extended to other 2D materials providing the same benefits that they afforded graphene.