1 research outputs found
Electronic Transport of Encapsulated Graphene and WSe<sub>2</sub> Devices Fabricated by Pick-up of Prepatterned hBN
We report high quality graphene and
WSe<sub>2</sub> devices encapsulated
between two hexagonal boron nitride (hBN) flakes using a pick-up method
with etched hBN flakes. Picking up prepatterned hBN flakes to be used
as a gate dielectric or mask for other 2D materials opens new possibilities
for the design and fabrication of 2D heterostructures. In this Letter,
we demonstrate this technique in two ways: first, a dual-gated graphene
device that is encapsulated between an hBN substrate and prepatterned
hBN strips. The conductance of the graphene device shows pronounced
Fabry–Pérot oscillations as a function of carrier density,
which implies strong quantum confinement and ballistic transport in
the locally gated region. Second, we describe a WSe<sub>2</sub> device
encapsulated in hBN with the top hBN patterned as a mask for the channel
of a Hall bar. Ionic liquid selectively tunes the carrier density
of the contact region of the device, while the hBN mask allows independent
tunability of the contact region for low contact resistance. Hall
mobility larger than 600 cm<sup>2</sup>/(V·s) for few-layer p-type
WSe<sub>2</sub> at 220 K is measured, the highest mobility of a thin
WSe<sub>2</sub> device reported to date. The observations of ballistic
transport in graphene and high mobility in WSe<sub>2</sub> confirm
pick-up of prepatterned hBN as a versatile technique to fabricate
ultraclean devices with high quality contact