5 research outputs found
Heterojunction Hybrid Devices from Vapor Phase Grown MoS
We investigate a vertically-stacked hybrid photodiode consisting of a thin
n-type molybdenum disulfide (MoS) layer transferred onto p-type silicon.
The fabrication is scalable as the MoS is grown by a controlled and
tunable vapor phase sulfurization process. The obtained large-scale p-n
heterojunction diodes exhibit notable photoconductivity which can be tuned by
modifying the thickness of the MoS layer. The diodes have a broad
spectral response due to direct and indirect band transitions of the nanoscale
MoS. Further, we observe a blue-shift of the spectral response into the
visible range. The results are a significant step towards scalable fabrication
of vertical devices from two-dimensional materials and constitute a new
paradigm for materials engineering.Comment: 23 pages with 4 figures. This article has been published in
Scientific Reports. (26 June 2014, doi:10.1038/srep05458
Optimizing the Optical and Electrical Properties of Graphene Ink Thin Films by Laser-annealing
We demonstrate a facile fabrication technique for graphene-based transparent
conductive films. Highly flat and uniform graphene films are obtained through
the incorporation of an efficient laser annealing technique with one-time drop
casting of high-concentration graphene ink. The resulting thin films are
uniform and exhibit a transparency of more than 85% at 550 nm and a sheet
resistance of about 30 k{\Omega}/sq. These values constitute an increase of 45%
in transparency, a reduction of surface roughness by a factor of four and a
decrease of 70% in sheet resistance compared to unannealed films.Comment: 18 pages, 4 figure
Coupling and cm propagation of long-range guided THz radiation in thin layers of water
We demonstrate the coupling of THz radiation in thin layers of water by means of attenuated total reflection measurements. Moreover, we excite this mode by end-fire coupling and experimentally show propagation lengths of 2 cm
Long-range guided THz radiation by thin layers of water
We propose a novel method to guide THz radiation with low losses along thin layers of water. This approach is based on the coupling of evanescent surface fields at the opposite sides of the thin water layer surrounded by a dielectric material, which leads to a maximum field amplitude at the interfaces and a reduction of the energy density inside the water film. In spite of the strong absorption of water in this frequency range, calculations show that the field distribution can lead to propagation lengths of several centimeters. By means of attenuated total reflection measurements we demonstrate the coupling of incident THz radiation to the long-range surface guided modes across a layer of water with a thickness of 24 µm. This first demonstration paves the way for THz sensing in aqueous environments