Molecular Layer-seeded Ultra-thin Top-gate Dielectrics for High Transconductance Graphene Transistors

The potential of graphene in integrated analog and digital circuits can only be fully realized through incorporation of ultra-thin gate dielectrics to enable large-scale small-channel graphene field-effect transistors (GFETs). Atomic-layer deposition (ALD) is a viable technique to fabricate gate-dielectrics, however, it requires a seeding layer on otherwise inert graphene. Here, we demonstrate a single molecule thick perylene-3,4,9,10-tetracarboxylic dianhydride overlayer as an effective seeding layer to grow high-$\kappa $ Al$_{2}$O$_{3}$ on mechanically exfoliated graphene for high-performance GFETs. Using an ultra-thin ($<$ 1nm) seeding layer, in contrast to polymer films (5-10 nm), we demonstrate fabrication of the thinnest ALD-grown gate-dielectric (4 nm) reported to date in top-gated GFETs. This yields high performance GFETs with the intrinsic transconductance parameter approaching 2.4 mS and the field-effect mobility $\sim $3000 cm$^{2}$/Vs. We also demonstrate generalization of this molecular layer seeded-ALD growth method to higher- $\kappa $ gate dielectrics, yielding further enhanced GFET transconductance for possible application to radio-frequency circuits.