44 research outputs found
Synthesis of Ultra-Thin Superionic Cu2Se and New Aspects of the Low-Temperature Crystal Configurations
Superionic conductors offer unique advantages for novel technological devices
in various fields, such as energy storage and neuromorphic computing. Above 414
K, Cu2Se turns into a well-known superionic conductor via a phase transition,
and it is demonstrated to exhibit peculiar electrical and thermoelectric
properties in bulk. Here, we report a large-area synthesis of ultra-thin single
crystalline Cu2Se using the chemical vapor deposition method. We demonstrate
that Cu2Se crystals exhibit optically and electrically controllable robust
phase reconfiguration below 414 K. Moreover, our results show that the mobility
of the liquid-like Cu ion vacancies in Cu2Se causes macroscopic fluctuations in
the Cu ordering. Consequently, phase variations are not dictated by the
diffusive motion of the ions but by the local energy minima formed due to the
interplay between the extrinsic and the intrinsic material parameters. As a
result, long-range ordering of the crystal below 414 K is optically observable
at a micrometer scale. Our results show that Cu2Se could find applications
beyond thermoelectric such as smart optical coatings, optoelectronic switching,
and ionic transistors
Non-invasive digital etching of van der Waals semiconductors
The capability to finely tailor material thickness with simultaneous atomic
precision and non-invasivity would be useful for constructing quantum platforms
and post-Moore microelectronics. However, it remains challenging to attain
synchronized controls over tailoring selectivity and precision. Here we report
a protocol that allows for non-invasive and atomically digital etching of van
der Waals transition-metal dichalcogenides through selective alloying via
low-temperature thermal diffusion and subsequent wet etching. The mechanism of
selective alloying between sacrifice metal atoms and defective or pristine
dichalcogenides is analyzed with high-resolution scanning transmission electron
microscopy. Also, the non-invasive nature and atomic level precision of our
etching technique are corroborated by consistent spectral, crystallographic and
electrical characterization measurements. The low-temperature charge mobility
of as-etched MoS reaches up to cmVs,
comparable to that of exfoliated pristine counterparts. The entire protocol
represents a highly precise and non-invasive tailoring route for material
manipulation.Comment: 46 pages, 4 figures, with S
Non-invasive digital etching of van der Waals semiconductors
The capability to finely tailor material thickness with simultaneous atomic precision and non-invasivity would be useful for constructing quantum platforms and post-Moore microelectronics. However, it remains challenging to attain synchronized controls over tailoring selectivity and precision. Here we report a protocol that allows for non-invasive and atomically digital etching of van der Waals transition-metal dichalcogenides through selective alloying via low-temperature thermal diffusion and subsequent wet etching. The mechanism of selective alloying between sacrifice metal atoms and defective or pristine dichalcogenides is analyzed with high-resolution scanning transmission electron microscopy. Also, the non-invasive nature and atomic level precision of our etching technique are corroborated by consistent spectral, crystallographic, and electrical characterization measurements. The low-temperature charge mobility of as-etched MoS2 reaches up to 1200 cm2 V−1s−1, comparable to that of exfoliated pristine counterparts. The entire protocol represents a highly precise and non-invasive tailoring route for material manipulation
Near-field Electrical Detection of Optical Plasmons and Single Plasmon Sources
Photonic circuits can be much faster than their electronic counterparts, but
they are difficult to miniaturize below the optical wavelength scale. Nanoscale
photonic circuits based on surface plasmon polaritons (SPs) are a promising
solution to this problem because they can localize light below the diffraction
limit. However, there is a general tradeoff between the localization of an SP
and the efficiency with which it can be detected with conventional far-field
optics. Here we describe a new all-electrical SP detection technique based on
the near-field coupling between guided plasmons and a nanowire field-effect
transistor. We use the technique to electrically detect the plasmon emission
from an individual colloidal quantum dot coupled to an SP waveguide. Our
detectors are both nanoscale and highly efficient (0.1 electrons/plasmon), and
a plasmonic gating effect can be used to amplify the signal even higher (up to
50 electrons/plasmon). These results enable new on-chip optical sensing
applications and are a key step towards "dark" optoplasmonic nanocircuits in
which SPs can be generated, manipulated, and detected without involving
far-field radiation.Comment: manuscript followed by supplementary informatio