Ion Beam Synthesis of Layer-Tunable and Transfer Free Graphene for Device Applications

Direct synthesis of layer-tunable and transfer-free graphene on technologically important substrates is highly valued for various electronics and device applications. State of the art in the field is currently a two-step process: a high-quality graphene layer synthesis on metal substrate through chemical vapor deposition (CVD) followed by delicate layer-transfer onto device-relevant substrates. Here, we report a novel synthesis approach combining ion implantation for a precise graphene layer control and dual-metal smart Janus substrate for a diffusion-limiting graphene formation, to directly synthesize large area, high quality, and layer-tunable graphene films on arbitrary substrates without the post-synthesis layer transfer process [1].<br/>Carbon (C) ion implantation was performed on Cu-Ni film deposited on a variety of device-relevant substrates. A well-controlled number of layers of graphene, primarily monolayer and bilayer, is precisely controlled by the equivalent fluence of the implanted C-atoms (1 monolayer ~ 4E15 C-atoms/cm2). Upon thermal annealing to promote Cu-Ni alloying, the pre-implanted C-atoms in the Ni layer are pushed towards the Ni/substrate interface by the top Cu layer due to the poor C-solubility in Cu. As a result, the expelled C-atoms precipitate into graphene structure at the interface facilitated by the Cu-like alloy catalysis. After removing the alloyed Cu-like surface layer, the layer-tunable graphene on the desired substrate is directly realized.<br/>This presentation will focus on graphene layer formation mechanism, detailed characterizations, and performance characteristics of select devices fabricated through this ion beam approach including near-IR photodetectors.<br/><br/><br/>[1] G.L. Zhang, J. Jiang, S.W. Yang, L. Zheng, G.Q. Ding, L. Song, X.H. Ju, Y.Q. Wang, C.C. Ye, and G. Wang, “Layer-Tunable and Transfer-Free Graphene on Arbitrary Substrates via Ion Beam Towards Versatile Applications”, Energy and Environmental Materials, 0 (2024) e12730.