nn9b05049_si_001.pdf (5.13 MB)
Enhanced Tunneling in a Hybrid of Single-Walled Carbon Nanotubes and Graphene
journal contribution
posted on 2019-09-18, 21:13 authored by Yongping Liao, Kimmo Mustonen, Semir Tulić, Viera Skákalová, Sabbir A. Khan, Patrik Laiho, Qiang Zhang, Changfeng Li, Mohammad R. A. Monazam, Jani Kotakoski, Harri Lipsanen, Esko I. KauppinenTransparent
and conductive films (TCFs) are of great technological
importance. Their high transmittance, electrical conductivity, and
mechanical strength make single-walled carbon nanotubes (SWCNTs) a
good candidate for the raw material for TCFs. Despite the ballistic
transport in individual SWCNTs, electrical conductivity of SWCNT networks
is limited by low efficiency of charge tunneling between the tube
elements. Here, we demonstrate that the nanotube network sheet resistance
at high optical transmittance is decreased by more than 50% when fabricated
on graphene. This is a comparable improvement as that
obtained through gold chloride (AuCl3) doping. However,
while Raman spectroscopy reveals substantial changes in spectral features of
AuCl3 doped nanotubes, this does not occur with graphene.
Instead, temperature-dependent transport measurements indicate that
a graphene substrate reduces the tunneling barrier heights, while
its parallel conductivity contribution is almost negligible. Finally,
we show that combining the graphene substrate and AuCl3 doping, brings the SWCNT thin film sheet resistance down
to 36 Ω/□.