Electroless Nickel Deposition: An Alternative for Graphene Contacting

We report the first investigation into the potential of electroless nickel deposition to form ohmic contacts on single layer graphene. To minimize the contact resistance on graphene, a statistical model was used to improve metal purity, surface roughness, and coverage of the deposited film by controlling the nickel bath parameters (pH and temperature). The metalized graphene layers were patterned using photolithography and contacts deposited at temperatures as low as 60 degrees C. The contact resistance was 215 +/- 23 Omega over a contact area of 200 mu m X 200 mu m, which improved upon rapid annealing to 107 +/- 9 Omega. This method shows promise toward low-cost and large-scale graphene integration into functional devices such as flexible sensors and printed electronics.