90 research outputs found
Fabrication and deterministic transfer of high quality quantum emitter in hexagonal boron nitride
Color centers in solid state crystals have become a frequently used system
for single photon generation, advancing the development of integrated photonic
devices for quantum optics and quantum communication applications. In
particular, defects hosted by two-dimensional (2D) hexagonal boron nitride
(hBN) are a promising candidate for next-generation single photon sources, due
to its chemical and thermal robustness and high brightness at room temperature.
The 2D crystal lattice of hBN allows for a high extraction efficiency and easy
integration into photonic circuits. Here we develop plasma etching techniques
with subsequent high temperature annealing to reliably create defects. We show
how different fabrication parameters influence the defect formation probability
and the emitter brightness. A full optical characterization reveals the higher
quality of the created quantum emitters, represented by a narrow spectrum,
short excited state lifetime and high single photon purity. We also
investigated the photostability on short and very long timescales. We utilize a
wet chemically-assisted transfer process to reliably transfer the single photon
sources onto arbitrary substrates, demonstrating the feasibility for the
integration into scalable photonic quantum information processing networks.Comment: revised versio
Hydrogenation and Hydro-Carbonation and Etching of Single-Walled Carbon Nanotubes
We present a systematic experimental investigation of the reactions between
hydrogen plasma and single-walled carbon nanotubes (SWNTs) at various
temperatures. Microscopy, infrared (IR) and Raman spectroscopy and electrical
transport measurements are carried out to investigate the properties of SWNTs
after hydrogenation. Structural deformations, drastically reduced electrical
conductance and increased semiconducting nature of SWNTs upon sidewall
hydrogenation are observed. These changes are reversible upon thermal annealing
at 500C via dehydrogenation. Harsh plasma or high temperature reactions lead to
etching of nanotube likely via hydro-carbonation. Smaller SWNTs are markedly
less stable against hydro-carbonation than larger tubes. The results are
fundamental and may have implications to basic and practical applications
including hydrogen storage, sensing, band-gap engineering for novel electronics
and new methods of manipulation, functionalization and etching of nanotubes.Comment: 3 pages, 4 figure
Space-compatible cavity-enhanced single-photon generation with hexagonal boron nitride
Sources of pure and indistinguishable single-photons are critical for
near-future optical quantum technologies. Recently, color centers hosted by
two-dimensional hexagonal boron nitride (hBN) have emerged as a promising
platform for high luminosity room temperature single-photon sources. Despite
the brightness of the emitters, the spectrum is rather broad and the
single-photon purity is not sufficient for practical quantum information
processing. Here, we report integration of such a quantum emitter hosted by hBN
into a tunable optical microcavity. A small mode volume of the order of
allows us to Purcell enhance the fluorescence, with the observed
excited state lifetime shortening. The cavity significantly narrows the
spectrum and improves the single-photon purity by suppression of off-resonant
noise. We explore practical applications by evaluating the performance of our
single-photon source for quantum key distribution and quantum computing. The
complete device is compact and implemented on a picoclass satellite platform,
enabling future low-cost satellite-based long-distance quantum networks
An optically-gated AuNP–DNA protonic transistor
Bio-interface transistors, which manipulate the transportation of ions (i.e. protons), play an important role in bridging physical devices with biological functionalities, because electrical signals are carried by ions/protons in biological systems. All available ionic transistors use electrostatic gates to tune the ionic carrier density, which requires complicated interconnect wires. In contrast, an optical gate, which offers the advantages of remote control as well as multiple light wavelength selections, has never been explored for ionic devices. Here, we demonstrate a light-gated protonic transistor fabricated from an Au nanoparticle and DNA (AuNP–DNA) hybrid membrane. The device can be turned on and off completely by using light, with a high on/off current ratio of up to 2 orders of magnitude. Moreover, the device only responds to specific light wavelengths due to the plasmonic effect from the AuNPs, which enables the capability of wavelength selectivity. Our results open up new avenues for exploring remotely controlled ionic circuits, in vivo protonic switches, and other biomedical applications
High-Efficiency Monolayer Molybdenum Ditelluride Light-Emitting Diode and Photodetector
Developing a high-efficiency and low-cost light source with emission wavelength transparent to silicon is an essential step toward silicon-based nanophotonic devices and micro/nano industry platforms. Here, a near-infrared monolayer MoTe2 light-emitting diode (LED) has been demonstrated and its emission wavelength is transparent to silicon. By taking advantage of the quantum tunneling effect, the device has achieved a very high external quantum efficiency (EQE) of 9.5% at 83 K, which is the highest EQE obtained from LED devices fabricated from monolayer TMDs so far. When the device is operated as a photodetector, the MoTe2 device exhibits a strong photoresponsivity at resonant wavelength 1145 nm. The low dark current of ∼5pA and fast response time 5.06 ms are achieved due to suppression of hBN tunneling layer. Our results open a new route for the investigation of novel near-infrared silicon integrated optoelectronic devicesThe authors acknowledge Financial support from ANU Ph.D. student scholarship, China Scholarship Council, ANU Major Equipment Committee fund (14MEC34), Australian Research Council (ARC) Discovery Early Career Researcher Award (DECRA) (DE140100805) and ARC Discovery Project (DP180103238)
Proton-driven patterning of bulk transition metal dichalcogenides
At the few-atom-thick limit, transition metal dichalcogenides (TMDs) exhibit
a host of attractive electronic optical, and structural properties. The
possibility to pattern these properties has a great impact on applied and
fundamental research. Here, we demonstrate spatial control over the light
emission, lattice deformation, and hydrogen storage in bulk TMDs. By low-energy
proton irradiation, we create uniquely favorable conditions for the production
and accumulation of molecular hydrogen just one or few monolayers beneath the
crystal basal plane of bulk WS2, WSe2, WTe2, MoSe2, and MoS2 samples. H2
therein produced coalesces to form bubbles, which lead to the localized
swelling of one X-M-X plane prevalently. This results eventually in the
creation of atomically thin domes filled with molecular hydrogen at 10 atm. The
domes emit light strongly well above room temperature and can store H2
indefinitely. They can be produced with the desired density, well-ordered
positions, and size tunable from the nanometer to the micrometer scale, thus
providing a template for the manageable and durable mechanical and electronic
structuring of two-dimensional materials
- …