We present results of atomic-force-microscopy-based friction measurements on Re-doped molybdenum disulfide (MoS2). In stark contrast to the widespread observation of decreasing friction with increasing number of layers on two-dimensional (2D) materials, friction on Re-doped MoS2 exhibits an anomalous, i.e., inverse dependence on the number of layers. Raman spectroscopy measurements combined with ab initio calculations reveal signatures of Re intercalation. Calculations suggest an increase in out-of-plane stiffness that inversely correlates with the number of layers as the physical mechanism behind this remarkable observation, revealing a distinctive regime of puckering for 2D materials.
This work reports
a one-pot chemical bath deposition (CBD) method
for the preparation of selectively grown, morphology-tunable zinc
oxide (ZnO) nanostructures provided via straightforward nanosecond
fiber laser ablation. Nanosecond fiber laser ablation is different
from lithographic methods due to its simple, time saving, and efficient
film scribing abilities. Here, multiple morphologies of the ZnO nanostructures
on the same substrate have been grown via laser ablation of the ZnO
seeding layer. Selective and controlled ablation of the titanium layer,
ZnO growth inhibitor, resulted in systematic growth of nanorod arrays,
while the application of extensive fluence energies resulted in the
penetration of the laser beam until the glass substrate induced the
nanoflake growth within the same CBD environment. The laser penetration
depth has been numerically investigated via COMSOL Multiphysics heat
module simulations, and the optical variations between two nanostructures
(nanorod and nanoflake) have been examined via Lumerical FDTD. The
simultaneous growth of two morphologies served as an efficient tool
for the enhancement of photoluminescence intensities. It increased
the average charge carrier lifetimes of the thin films from approximately
2.01 to 9.07 ns under the same excitation wavelengths. The amplification
in PL performances has been accomplished via the capstone of all-inorganic
halide perovskite (IHP) deposition that brought a successful conclusion
to lifetime responses, which have been increased by 1.4-fold. The
development of IHP sensitized nanoscaled multimorphological ZnO thin
films can, therefore, be used as potential nanomaterials for light-emitting-device
applications.
We have fabricated a four-element graphene/silicon on insulator (SOI) based Schottky barrier photodiode array (PDA) and investigated its optoelectronic device performance. In our device design, monolayer graphene is utilized as a common electrode on a lithographically defined linear array of n-type Si channels on a SOI substrate. As revealed by wavelength resolved photocurrent spectroscopy measurements, each element in the PDA structure exhibited a maximum spectral responsivity of around 0.1 A/W under a self-powered operational mode. Time-dependent photocurrent spectroscopy measurements showed excellent photocurrent reversibility of the device with ∼1.36 and ∼1.27 μs rise time and fall time, respectively. Each element in the array displayed an average specific detectivity of around 1.3 × 1012 Jones and a substantially small noise equivalent power of ∼0.14 pW/Hz−1/2. The study presented here is expected to offer exciting opportunities in terms of high value-added graphene/Si based PDA device applications such as multi-wavelength light measurement, level metering, high-speed photometry, and position/motion detection.
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