arXiv subjects

Juan Xia

Publications and source records attributed to Juan Xia.

3 recordsLinked to original sources

arXiv2024

Integrating of continuous graphene with periodic ferroelectric domains for adaptive terahertz photodetector

Graphene plasmons hold immense potential for terahertz (THz) detector application due to their fascinating interactions between radiation and matter. However, it has remained challenging to excite and manipulate graphene plasmons within continuous graphene that is free of patterning technique. Here, we report an adaptive wavelength-sensitive terahertz detector consisting of continuous graphene integrated onto a ferroelectric thin film with periodic polarization domains. This designed device is capable of absorbing THz waves with zero input bias voltage because of highly confinement of surface plasmons within the interface between graphene and ferroelectrics. By reconfiguring an interweaving squared ferroelectric domain array with alternating upward and downward polarizations, our devices theoretically own an ultrahigh responsivity of 17.56 A W-1 and a specific detectivity of 1.11*10^11 Jones at room temperature. We also demonstrate that the photodetectors make possible for spectrum reconstruction application of portable spectrometer at a broad operation band of 4.97 to 7.85 THz with resolution up to 0.02 THz combining the mathematical algorithms.

physics.optics↗

arXiv2023

Bright nonblinking photoluminescence with blinking lifetime from a nanocavity-coupled quantum dot

Colloidal semiconductor quantum dots (QDs) are excellent luminescent nanomaterials for a broad range of optoelectronic applications. Their photoluminescence blinking, however, hinders their practical use in many aspects. It has been shown that coupling QDs to plasmonic nanostructures may provide a viable way to suppress blinking. Nevertheless, the underlying mechanism of blinking suppression remains unclear and debated. Here, by deterministically coupling a single QD to a plasmonic nanocavity, we clarify the mechanism of blinking suppression, and demonstrate unprecedentedly bright emission from a single colloidal QD. In particular, we report for the first time that the coupled system exhibits nonblinking photoluminescence with blinking lifetime, which shows that the elimination of photoluminescence blinking originates from enhanced quantum yield of the charged states. We identify that the radiative decay rate is boosted from (48 ns)-1 to (0.7 ns)-1, which outcompetes Auger processes and enables similar quantum yields for charged and neutral excitons. Moreover, we demonstrate ultrabright photoluminescence of up to 17 million detected photons per second from a single QD. This work sheds new light on the goal of achieving ultrabright nonblinking QDs and may benefit a variety of QD-based applications.

physics.optics↗

arXiv2016

Large-area and high-quality 2D transition metal telluride

Atomically thin transitional metal ditellurides like WTe2 and MoTe2 have triggered tremendous research interests because of their intrinsic nontrivial band structure. They are also predicted to be 2D topological insulators and type-II Weyl semimetals. However, most of the studies on ditelluride atomic layers so far rely on the low-yield and time-consuming mechanical exfoliation method. Direct synthesis of large-scale monolayer ditellurides has not yet been achieved. Here, using the chemical vapor deposition (CVD) method, we demonstrate controlled synthesis of high-quality and atom-thin tellurides with lateral size over 300 μm. We found that the as-grown WTe2 maintains two different stacking sequences in the bilayer, where the atomic structure of the stacking boundary is revealed by scanning transmission electron microscope (STEM). The low-temperature transport measurements revealed a novel semimetal-to-insulator transition in WTe2 layers and an enhanced superconductivity in few-layer MoTe2. This work paves the way to the synthesis of atom-thin tellurides and also quantum spin Hall devices.

cond-mat.mtrl-sci↗