Graphene on Silicon Hybrid Field-Effect Transistors

• Main Authors: Fomin, Mykola, Pasadas, Francisco, Marin, Enrique, Rull, Alberto Medina, Ruiz, Francisco, Godoy, Andres, Zadorozhnyi, Ihor, Beltramo, Guillermo, Brings, Fabian, Vitusevich, Svetlana, Offenhaeusser, Andreas, Kireev, Dmitry
• Format: Journal Article
• Language: English
• Published: 20-04-2022
• Subjects: Physics - Applied Physics; Physics - Mesoscale and Nanoscale Physics
• DOI: 10.48550/arxiv.2204.09572

The combination of graphene with silicon in hybrid devices has attracted
attention extensively over the last decade. Most of such devices were proposed
for photonics and radiofrequency applications. In this work, we present a
unique technology of graphene-on-silicon heterostructures and their properties
as solution-gated transistors. The graphene-on-Silicon field-effect transistors
(GoSFETs) were fabricated exploiting various conformations of drain-source
regions doping and channel material dimensions. The fabricated devices were
electrically characterized demonstrating hybrid behavior with features specific
to both graphene and silicon. Although GoSFET's transconductance and carrier's
mobility were found to be lower than in conventional silicon and graphene
field-effect transistors (SiFETs and GFETs), it was demonstrated that the
combination of both materials within the hybrid channel contribute uniquely to
the charge carrier transport. A comprehensive physics-based compact modeling
was specifically developed, showing excellent agreement with the experimental
data. The model is employed to rationalize the observed hybrid behavior as the
theoretical results from the electrostatics and the carrier transport under a
drift-diffusion approach show that graphene acts as a shield for the silicon
channel, giving rise to a non-uniform potential distribution along it,
especially at the subthreshold region. This graphene screening effect is shown
to strongly affect the device subthreshold swing when compared against a
conventional SiFET due to a non-negligible diffusion current in this operation
regime.