Single Quantum Dot Selection and Tailor-Made Photonic Device Integration using a Nanoscale-Focus Pinspot.

Among the diverse platforms of quantum light sources, epitaxially grown semiconductor quantum dots (QDs) are one of the most attractive workhorses for realizing quantum photonic technologies owing to their outstanding brightness and scalability. However, the spatial and spectral randomness of most QDs severely hinders the construction of large-scale photonic platforms. In this work, a methodology is presented to deterministically integrate single QDs with tailor-made photonic structures.

SWIR imaging using PbS QD photodiode array sensors.

We fabricated a 1 × 10 PbS QD photodiode array with multiple stacked QD layers with high-resolution patterning using a customized photolithographic process. The array showed the average responsivity of 5.54 × 10 A/W and 1.

Temperature-Dependent Exciton Dynamics in a Single GaAs Quantum Ring and a Quantum Dot.

Micro-photoluminescence was observed while increasing the excitation power in a single GaAs quantum ring (QR) at 4 K. Fine structures at the energy levels of the ground ( = 1) and excited ( = 2) state excitons exhibited a blue shift when excitation power increased. The excited state exciton had a strong polarization dependence that stemmed from the asymmetric localized state.

Energy-Efficient III-V Tunnel FET-Based Synaptic Device with Enhanced Charge Trapping Ability Utilizing Both Hot Hole and Hot Electron Injections for Analog Neuromorphic Computing.

A charge trap device based on field-effect transistors (FET) is a promising candidate for artificial synapses because of its high reliability and mature fabrication technology. However, conventional MOSFET-based charge trap synapses require a strong stimulus for synaptic update because of their inefficient hot-carrier injection into the charge trapping layer, consequently causing a slow speed operation and large power consumption. Here, we propose a highly efficient charge trap synapse using III-V materials-based tunnel field-effect transistor (TFET).

Coherence in cooperative photon emission from indistinguishable quantum emitters.

Photon-mediated interactions between atoms can arise via coupling to a common electromagnetic mode or by quantum interference. Here, we probe the role of coherence in cooperative emission arising from two distant but indistinguishable solid-state emitters because of path erasure. The primary signature of cooperative emission, the emergence of "bunching" at zero delay in an intensity correlation experiment, is used to characterize the indistinguishability of the emitters, their dephasing, and the degree of correlation in the joint system that can be coherently controlled.

Optical characteristics of type-II hexagonal-shaped GaSb quantum dots on GaAs synthesized using nanowire self-growth mechanism from Ga metal droplet.

We report the growth mechanism and optical characteristics of type-II band-aligned GaSb quantum dots (QDs) grown on GaAs using a droplet epitaxy-driven nanowire formation mechanism with molecular beam epitaxy. Using transmission electron microscopy and scanning electron microscopy images, we confirmed that the QDs, which comprised zinc-blende crystal structures with hexagonal shapes, were successfully grown through the formation of a nanowire from a Ga droplet, with reduced strain between GaAs and GaSb. Photoluminescence (PL) peaks of GaSb capped by a GaAs layer were observed at 1.

Comparative Chemico-Physical Analyses of Strain-Free GaAs/AlGaAs Quantum Dots Grown by Droplet Epitaxy.

We investigate the quantum confinement effects on excitons in several types of strain-free GaAs/Al 0 . 3 Ga 0 . 7 As droplet epitaxy (DE) quantum dots (QDs).

Optical shaping of the polarization anisotropy in a laterally coupled quantum dot dimer.

We find that the emission from laterally coupled quantum dots is strongly polarized along the coupled direction [1 0], and its polarization anisotropy can be shaped by changing the orientation of the polarized excitation. When the nonresonant excitation is linearly polarized perpendicular to the coupled direction [110], excitons (X and X) and local biexcitons (XX and XX) from the two separate quantum dots (QD and QD) show emission anisotropy with a small degree of polarization (10%). On the other hand, when the excitation polarization is parallel to the coupled direction [1 0], the polarization anisotropy of excitons, local biexcitons, and coupled biexcitons (XX) is enhanced with a degree of polarization of 74%.

Self-Powered Visible-Invisible Multiband Detection and Imaging Achieved Using High-Performance 2D MoTe/MoS Semivertical Heterojunction Photodiodes.

Two-dimensional (2D) van der Waals (vdW) heterostructures herald new opportunities for conducting fundamental studies of new physical/chemical phenomena and developing diverse nanodevice applications. In particular, vdW heterojunction p-n diodes exhibit great potential as high-performance photodetectors, which play a key role in many optoelectronic applications. Here, we report on 2D MoTe/MoS multilayer semivertical vdW heterojunction p-n diodes and their optoelectronic application in self-powered visible-invisible multiband detection and imaging.

Strain-induced control of a pillar cavity-GaAs single quantum dot photon source.

Herein, we present the calculated strain-induced control of single GaAs/AlGaAs quantum dots (QDs) integrated into semiconductor micropillar cavities. We show precise energy control of individual single GaAs QD excitons under multi-modal stress fields of tailored micropillar optomechanical resonators. Further, using a three-dimensional envelope-function model, we evaluated the quantum mechanical correction in the QD band structures depending on their geometrical shape asymmetries and, more interestingly, on the practical degree of Al interdiffusion.

InAs on GaAs Photodetectors Using Thin InAlAs Graded Buffers and Their Application to Exceeding Short-Wave Infrared Imaging at 300 K.

Short-wave infrared (SWIR) detectors and emitters have a high potential value in several fields of applications, including the internet of things (IoT) and advanced driver assistance systems (ADAS), gas sensing. Indium Gallium Arsenide (InGaAs) photodetectors are widely used in the SWIR region of 1-3 μm; however, they only capture a part of the region due to a cut-off wavelength of 1.7 μm.

Indistinguishable Photons from Deterministically Integrated Single Quantum Dots in Heterogeneous GaAs/SiN Quantum Photonic Circuits.

Silicon photonics enables scaling of quantum photonic systems by allowing the creation of extensive, low-loss, reconfigurable networks linking various functional on-chip elements. Inclusion of single quantum emitters onto photonic circuits, acting as on-demand sources of indistinguishable photons or single-photon nonlinearities, may enable large-scale chip-based quantum photonic circuits and networks. Toward this, we use low-temperature in situ electron-beam lithography to deterministically produce hybrid GaAs/SiN photonic devices containing single InAs quantum dots precisely located inside nanophotonic structures, which act as efficient, SiN waveguide-coupled on-chip, on-demand single-photon sources.

Erratum: High-Quality 100 nm Thick InSb Films Grown on GaAs(001) Substrates with an In Al Sb Continuously Graded Buffer Layer.

[This corrects the article DOI: 10.1021/acsomega.8b02189.

Post-thermal-Induced Recrystallization in GaAs/AlGaAs Quantum Dots Grown by Droplet Epitaxy with Near-Unity Stoichiometry.

Here, we investigate the stoichiometry control of GaAs/AlGaAs droplet epitaxy (DE) quantum dots (QDs). Few tens of core nonstoichiometries in the Ga(As) atomic percent are revealed in as-grown "strain-free" QDs using state-of-the-art atomic-scale energy-dispersive X-ray spectroscopy based on transmission electron microscopy. Precise systematic analyses demonstrate a successful quenching of the nonstoichiometry below 2%.

High-Quality 100 nm Thick InSb Films Grown on GaAs(001) Substrates with an In Al Sb Continuously Graded Buffer Layer.

In this paper, we report the growth of a high-quality 100 nm thick InSb layer on a (001) GaAs substrate for InSb-based high-speed electronic device applications. A continuously graded buffer (CGB) technique with In Al Sb was used to grow high-quality InSb films on GaAs substrates. The CGB layer was grown by continuously changing the growth temperature and composition of the aluminum and indium during the growth of the buffer layer.

How do plants see the world? - UV imaging with a TiO nanowire array by artificial photosynthesis.

The concept of plant vision refers to the fact that plants are receptive to their visual environment, although the mechanism involved is quite distinct from the human visual system. The mechanism in plants is not well understood and has yet to be fully investigated. In this work, we have exploited the properties of TiO2 nanowires as a UV sensor to simulate the phenomenon of photosynthesis in order to come one step closer to understanding how plants see the world.

Deterministic Integration of Quantum Dots into on-Chip Multimode Interference Beamsplitters Using in Situ Electron Beam Lithography.

The development of multinode quantum optical circuits has attracted great attention in recent years. In particular, interfacing quantum-light sources, gates, and detectors on a single chip is highly desirable for the realization of large networks. In this context, fabrication techniques that enable the deterministic integration of preselected quantum-light emitters into nanophotonic elements play a key role when moving forward to circuits containing multiple emitters.

GaAs droplet quantum dots with nanometer-thin capping layer for plasmonic applications.

We report on the growth and optical characterization of droplet GaAs quantum dots (QDs) with extremely-thin (11 nm) capping layers. To achieve such result, an internal thermal heating step is introduced during the growth and its role in the morphological properties of the QDs obtained is investigated via scanning electron and atomic force microscopy. Photoluminescence measurements at cryogenic temperatures show optically stable, sharp and bright emission from single QDs, at visible wavelengths.

Single self-assembled InAs/GaAs quantum dots in photonic nanostructures: The role of nanofabrication.

Single self-assembled InAs/GaAs quantum dots are a promising solid-state quantum technology, with which vacuum Rabi splitting, single-photon-level nonlinearities, and bright, pure, and indistinguishable single-photon generation having been demonstrated. For such achievements, nanofabrication is used to create structures in which the quantum dot preferentially interacts with strongly-confined optical modes. An open question is the extent to which such nanofabrication may also have an adverse influence, through the creation of traps and surface states that could induce blinking, spectral diffusion, and dephasing.

Generalized Scheme for High Performing Photodetectors with a p-Type 2D Channel Layer and n-Type Nanoparticles.

A generalized scheme for the fabrication of high performance photodetectors consisting of a p-type channel material and n-type nanoparticles is proposed. The high performance of the proposed hybrid photodetector is achieved through enhanced photoabsorption and the photocurrent gain arising from its effective charge transfer mechanism. In this paper, the realization of this design is presented in a hybrid photodetector consisting of 2D p-type black phosphorus (BP) and n-type molybdenum disulfide nanoparticles (MoS NPs), and it is demonstrated that it exhibits enhanced photoresponsivity and detectivity compared to pristine BP photodetectors.

Quantum cascade lasers with YO insulation layer operating at 8.1 µm.

SiO is a commonly used insulation layer for QCLs but has high absorption peak around 8 to 10 µm. Instead of SiO, we used YO as an insulation layer for DC-QCL and successfully demonstrated lasing operation at the wavelength around 8.1 µm.

Electrical properties and thermal stability in stack structure of HfO/AlO/InSb by atomic layer deposition.

Changes in the electrical properties and thermal stability of HfO grown on AlO-passivated InSb by atomic layer deposition (ALD) were investigated. The deposited HfO on InSb at a temperature of 200 °C was in an amorphous phase with low interfacial defect states. During post-deposition annealing (PDA) at 400 °C, In-Sb bonding was dissociated and diffusion through HfO occurred.

Combined atomic force microscopy and photoluminescence imaging to select single InAs/GaAs quantum dots for quantum photonic devices.

We report on a combined photoluminescence imaging and atomic force microscopy study of single, isolated self-assembled InAs quantum dots. The motivation of this work is to determine an approach that allows to assess single quantum dots as candidates for quantum nanophotonic devices. By combining optical and scanning probe characterization techniques, we find that single quantum dots often appear in the vicinity of comparatively large topographic features.

Acousto-optic modulation and opto-acoustic gating in piezo-optomechanical circuits.

Acoustic wave devices provide a promising chip-scale platform for efficiently coupling radio frequency (RF) and optical fields. Here, we use an integrated piezo-optomechanical circuit platform that exploits both the piezoelectric and photoelastic coupling mechanisms to link 2.4 GHz RF waves to 194 THz (1550 nm) optical waves, through coupling to propagating and localized 2.