We demonstrated a simple and scalable fabrication route of a nitrogen-doped reduced graphene oxide (N-rGO) photodetector on an 8 in. wafer-scale. The N-rGO was prepared through in situ plasma treatment in an acetylene-ammonia atmosphere to achieve an n-type semiconductor with substantial formation of quaternary-N substituted into the graphene lattice. The morphology, structural, chemical composition, and electrical properties of the N-rGO were carefully characterized and used for the device fabrication. The N-rGO devices were fabricated in a simple metal−semiconductor−metal structure with unconventional metal-on-bottom configuration to promote high-performance photodetection. The N-rGO devices exhibited enhanced photoresponsivity as high as 0.68 A W −1 at 1.0 V, which is about 2 orders of magnitude higher compared to a pristine graphene and wide-band photoinduced response from the visible to the near-infrared region with increasing sensitivity in the order of 785, 632.8, and 473 nm excitation wavelengths. We also further demonstrated a symmetric characteristic of the photoinduced response to any position of local laser excitation with respect to the electrodes. The excellent features of waferscale N-rGO devices suggest a promising route to merge the current silicon technology and two-dimensional materials for future optoelectronic devices.
We report a practical
chemical vapor deposition (CVD) route to
produce bilayer graphene on a polycrystalline Ni film from liquid
benzene (C
6
H
6
) source at a temperature as low
as 400 °C in a vertical cold-wall reaction chamber. The low activation
energy of C
6
H
6
and the low solubility of carbon
in Ni at such a low temperature play a key role in enabling the growth
of large-area bilayer graphene in a controlled manner by a Ni surface-mediated
reaction. All experiments performed using this method are reproducible
with growth capabilities up to an 8 in. wafer-scale substrate. Raman
spectra analysis, high-resolution transmission electron microscopy,
and selective area electron diffraction studies confirm the growth
of Bernal-stacked bilayer graphene with good uniformity over large
areas. Electrical characterization studies indicate that the bilayer
graphene behaves much like a semiconductor with predominant p-type
doping. These findings provide important insights into the wafer-scale
fabrication of low-temperature CVD bilayer graphene for next-generation
nanoelectronics.
We
report a viable
method to produce nanocrystalline graphene films
on polycrystalline nickel (Ni) with enhanced N doping at low temperatures
by a cold-wall plasma-assisted chemical vapor deposition (CVD) method.
The growth of nanocrystalline graphene films was carried out in a
benzene/ammonia/argon (C6H6/NH3/Ar)
system, in which the temperature of the substrate heated by Joule
heating can be further lowered to 100 °C to achieve a low sheet
resistance of 3.3 kΩ sq–1 at a high optical
transmittance of 97.2%. The morphological, structural, and electrical
properties and the chemical compositions of the obtained N-doped nanocrystalline
graphene films can be tailored by controlling the growth parameters.
An increase in the concentration of atomic N from 1.42 to 11.28 atomic
percent (at.%) is expected due to the synergetic effects of a high
NH3/Ar ratio and plasma power. The possible growth mechanism
of nanocrystalline graphene films is also discussed to understand
the basic chemical reactions that occur at such low temperatures with
the presence of plasma as well as the formation of pyridinic-N- and
pyrrolic-N-dominated nanocrystalline graphene. The realization of
nanocrystalline graphene films with enhanced N doping at 100 °C
may open great potential in developing future transparent nanodevices.
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