Large-Scale Graphene on Hexagonal-BN Hall Elements: Prediction of Sensor Performance without Magnetic Field

A graphene Hall element (GHE) is
an optimal system for a magnetic
sensor because of its perfect two-dimensional (2-D) structure, high
carrier mobility, and widely tunable carrier concentration. Even though
several proof-of-concept devices have been proposed, manufacturing
them by mechanical exfoliation of 2-D material or electron-beam lithography
is of limited feasibility. Here, we demonstrate a high quality GHE
array having a graphene on hexagonal-BN (h-BN) heterostructure,
fabricated by photolithography and large-area 2-D materials grown
by chemical vapor deposition techniques. A superior performance of
GHE was achieved with the help of a bottom h-BN layer,
and showed a maximum current-normalized sensitivity of 1986 V/AT,
a minimum magnetic resolution of 0.5 mG/Hz0.5 at f = 300 Hz, and an effective dynamic range larger than 74
dB. Furthermore, on the basis of a thorough understanding of the shift
of charge neutrality point depending on various parameters, an analytical
model that predicts the magnetic sensor operation of a GHE from its
transconductance data without magnetic field is proposed, simplifying
the evaluation of each GHE design. These results demonstrate the feasibility
of this highly performing graphene device using large-scale manufacturing-friendly
fabrication methods.