Polymethylmethacrylate (PMMA) deposition and removal optimization in CVD-grown graphene transfer: A Taguchi technique study

The conventional method of graphene transfer involving Polymethylmethacrylate (PMMA) often results in residual PMMA, negatively impacting the optical and electrical properties of the transferred graphene layer. This study employs the Taguchi optimization technique to minimize PMMA contamination during the graphene transfer process. The quality of the transferred graphene layer was evaluated utilizing atomic force microscopy (AFM), Raman spectroscopy, and Hall Effect measurement. The optimized conditions identified were a PMMA concentration (P) of 4.5 %, a spin rotation (S) speed of 3000 rpm, an acetone bath temperature (A) at 40 °C, and a dissolution duration (T) of 60 min. These parameters achieved a promising surface coverage of 3.42 %. Interestingly, further characterization highlighted that sample #8, prepared with different parameters (P = 12 %, S = 3000 rpm, A = 24 °C, T = 60 min), exhibited a surface coverage of 5.10 % and superior properties, including high transparency, exceptional film quality, low electrical resistance (8691 Ω), and an I_D/I_G ratio of 0.13. These findings suggest that the optimized conditions are suitable for applications prioritizing surface coverage, while the parameters for sample #8 are recommended for achieving minimal electrical resistance, high transparency, and superior film quality. This research contributes insights into PMMA-assisted graphene transfer, offering practical guidance for tailored processes.