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PVL multiple arms with a circular groove can be used to rotate a microparticle in the far-field region.

Particle levitation is crucial in optical trapping considering contamination and alteration of the character of the particle due to physical contact with the structure. A strong field gradient along the optical axis is required in this case. To manipulate the particle at a distance from the surface, we propose an Archimedes spiral plasmonic lens with a circular groove (CG-ASPL). The optical properties and parameters influencing the trapping performance of CG-ASPL are fully analyzed and discussed. By illuminating the structure with circular polarization and structure optimization, we can reduce the required optical power down to 2.4 mW for trapping particle of 1 µm in diameter with groove width and height of 100 and 125 nm, respectively. The particle can be stably trapped with trapping potential of 4138 kBT/W in the far-field region (1.1λ) owing to constructive interference of the scattered SPP waves. Furthermore, this structure is ultra-compact with a size of about 6.7 µm in diameter. We believe the results demonstrated in this work would be very useful for lab-on-a-chip applications and many others.

In recent years, the process requirements of nano-devices have led to the gradual reduction in the scale of semiconductor devices, and the consequent non-negligible sidewall defects caused by etching. Since plasma-enhanced chemical vapor deposition can no longer provide sufficient step coverage, the characteristics of atomic layer deposition ALD technology are used to solve this problem. ALD utilizes self-limiting interactions between the precursor gas and the substrate surface. When the reactive gas forms a single layer of chemical adsorbed on the substrate surface, no reaction occurs between them and the growth thickness can be controlled. At the Å level, it can provide good step coverage. In this study, recent research on the ALD passivation on micro-light-emitting diodes and vertical cavity surface emitting lasers was reviewed and compared. Several passivation methods were demonstrated to lead to enhanced light efficiency, reduced leakage, and improved reliability.

In this work, we investigated the effect of the tungsten nitride (WNx) diffusion barrier layer on the resistive switching operation of the aluminum nitride (AlN) based conductive bridge random access memory. The WNx barrier layer limits the diffusion of Cu ions in the AlN switching layer, hence controlling the formation of metallic conductive filament in the host layer. The device operated at a very low operating voltage with a Vset of 0.6 V and a Vreset of 0.4 V. The spatial and temporal switching variability were reduced significantly by inserting a barrier layer. The worst-case coefficient of variations (σ/µ) for HRS and LRS are 33% and 18%, respectively, when barrier layer devices are deployed, compared to 167% and 33% when the barrier layer is not present. With a barrier layer, the device exhibits data retention behavior for more than 104 s at 120 °C, whereas without a barrier layer, the device fails after 103 s. The device demonstrated synaptic behavior with long-term potentiation/depression (LTP/LTD) for 30 epochs by stimulating with a train of identical optimized pulses of 1 µs duration.

In this report, we propose an idea of connecting 1D photonic crystal (PhC) nanocavity with novel waveguide-like strain shapers in a polydimethylsiloxane substrate. In theory, the induced film-edge strain by the strain shapers can significantly enhance the wavelength tunability of PhC nanocavity under different applied stress. By our nanofabrication process, we realize this idea in the form of a tunable nanolaser. In experiments, the nanolaser shows the enhanced wavelength tunability both under stretching and compressive stress. By investigating the effects of PhC periods and length of the strain shapers, we obtain an optimized lasing wavelength tunability of −13.9 nm under every percentage strain variation in experiments. When further taking the 2nd -order mode in the nanocavity into consideration, we observe a wide lasing wavelength tuning range over 160 nm, which takes only the applied strain $\Delta \xi _{tot}$ of ±0.05. In addition to the large wavelength response beneficial for tunable nanolasers and optical strain sensors, we also believe that this waveguide-like strain shapers can serve as the optical interconnections at the same time in the flexible photonic circuits.

Layer-by-layer graphene growth is demonstrated by repeating CVD growth cycles directly on sapphire substrates. Improved field-effect mobility values are observed for the bottom-gate transistors fabricated by using the bilayer graphene channel, which indicates an improved crystallinity is obtained after the second CVD growth cycle. Despite the poor wettability of copper on graphene surfaces, graphene may act as a thin and effective diffusion barrier for copper atoms. The low resistivity values of thin copper films deposited on thin monolayer MoS

We demonstrate a photonic crystal laser embedded in a polymeric thin film, which can attach to the object's surface and show significant wavelength responses in bending, pressing, and gas pressure sensing via nanoclamps with strain-shaping.

Replacing precious metals with low-cost metals is the best solution for large scale production. Copper is known for its excellent conductivity and thermal management applications. When it comes to hydrogen evolution reaction, it is highly unstable, especially in KOH solution. In this paper, we approached a simple method to reduce corrosion and improve the performance by depositing nickel-molybdenum oxide and nickel on copper substrates and the achieved tafel slopes of 115 mV/dec and 117 mV/dec at 10 mA/cm2. While at first, molybdenum oxide coated samples showed better performance after 100 cycles of stability tests, the onset potential rapidly changed. Cu-Ni, which was deposited using the electron gun evaporation (e-gun), has shown better performance with 0.28 V at 10 mA/cm2 and led to stability after 100 cycles. Our results show that when copper is alloyed with nickel, it acts as a promising hydrogen evolution reaction (HER) catalyst.

By a high precision transfer printing, we realize efficient light coupling between SiNx waveguide and 1D photonic crystal nanobeam laser with asymmetric/tapered structures. We also study the influence of integration misalignment on light coupling.

A few-mode VCSEL has an oxide-confined aperture of 6 µm and a heavily Zn-diffusion aperture of 4 µm, which is demonstrated a -3-dB E-O bandwidth (26.5 GHz), and passed 50 Gb/s pre-emphasis NRZ-OOK transmission over 100 m GI-SMF links.

Boron (B)-doped gradient Si-rich oxide multilayer (GSRO-ML) structure is utilized to realize super-high density Si quantum dots (QDs) thin films with large carrier tunneling probability by co-sputtering. The B-doping effect on crystalline, optical, electrical and photovoltaic (PV) properties of Si QD thin films is investigated in this study. With increased B-doping concentration, the preserved high crystallinity of Si QDs and the reduced optical bandgap are observed. An optimized doping condition is found for the electrical and PV properties. Further increasing the doping concentration leads to increased inactive B atoms and interfacial over-diffusion. The issue of interfacial over-diffusion can be efficiently improved by inserting lowly B-doped GSRO-ML thin films. Our results show the feasibility and great potential for high efficiency Si-based solar cells integrating Si QDs by properly doped B atoms in GSRO-ML thin film structure.

In this study, by combining a large-area MoS2 monolayer with silver plasmonic nanostructures in a deformable polydimethylsiloxane substrate, we theoretically and experimentally studied the photoluminescence (PL) enhancement of MoS2 by surface lattice resonance (SLR) modes of different silver plasmonic nanostructures. We also observed the stable PL enhancement of MoS2 by silver nanodisc arrays under differently applied stretching strains, caused by the mechanical holding effect of the MoS2 monolayer. We believe the results presented herein can guarantee the possibility of stably enhancing the light emission of transition metal dichalcogenides using SLR modes in a deformable platform.

High-quality epitaxial layers are directly related to internal quantum efficiency. The methods used to design such epitaxial layers are reviewed in this article. The ultraviolet C (UVC) light-emitting diode (LED) epitaxial layer structure exhibits electron leakage; therefore, many research groups have proposed the design of blocking layers and carrier transportation to generate high electron–hole recombination rates. This also aids in increasing the internal quantum efficiency. The cap layer, p-GaN, exhibits high absorption in deep UV radiation; thus, a small thickness is usually chosen. Flip chip design is more popular for such devices in the UV band, and the main factors for consideration are light extraction and heat transportation. However, the choice of encapsulation materials is important, because unsuitable encapsulation materials will be degraded by ultraviolet light irradiation. A suitable package design can account for light extraction and heat transportation. Finally, an atomic layer deposition Al2O3 film has been proposed as a mesa passivation layer. It can provide a low reverse current leakage. Moreover, it can help increase the quantum efficiency, enhance the moisture resistance, and improve reliability. UVC LED applications can be used in sterilization, water purification, air purification, and medical and military fields.

A few-mode VCSEL has an oxide-confined aperture of 6 μm and a heavily Zn-diffusion aperture of 4 μm, which is demonstrated a -3-dB E-O bandwidth (26.5 GHz), and passed 50 Gb/s pre-emphasis NRZ-OOK transmission over 100 m GI-SMF links.

Localized surface plasmon resonance (LSPR) in different metallic nanostructures with sharp field gradient and extremely strong field intensity below the diffraction limit are the keys of near-field optical nano-tweezers for efficiently manipulating tiny bio-object. To further enhance the field gradient and intensity of LSPR and improve accessibility for the target object in nano-tweezers, we propose and realize a plasmonic bowtie notch design with assisted curved grooves for coupling more surface plasmon polariton waves into the LSPR. In experiments, our presented design shows the improved low power consumption for stably trapping bio-sized particles, which is promising for realizing an efficient nano-tweezers.

In the present study, novel MoS2 bilayers with 3D structures were considered for their application as wavelength-sensitive photodetectors. Using e-gun deposition and a CVD process, MoS2 bilayers can be grown conformally on a patterned (cones or pyramids) sapphire substrate without any wrinkles on the 2D film. After the sulfurization process, the MoS2 bilayer is subjected to a local strain in the patterns and its band gap gets enlarged due to the strain. This phenomenon is beneficial for photo-devices to enable the collection of the photocurrent. Measurements revealed a broadband enhancement of the MoS2-based photodetector with a patterned array in terms of both absorption and photocurrent. It is noteworthy that a cone-patterned sapphire substrate (CPSS) is able to generate more photocurrent when illuminated under blue light illumination, whereas the pyramid-patterned sapphire substrate (PPSS) performs best under green and red light illumination. Simulations of the electric field distributions for MoS2 coatings on different substrates, based on 3D models, revealed that the sensitivity of the MoS2-based photodetector can be greatly enhanced by the light-scattering effect.

We introduce a photonic crystal nanocavity consisting of one-dimensional periodic nanorods embedded in a deformable polydimethylsiloxane substrate, which exhibits a high-quality factor and a large wavelength response to the applied strain. By further investigating its wavelength response to nonaxial planar strains, we propose and experimentally demonstrate a sensor unit that can precisely identify different planar strains, including their application direction, type, and value. This sensor prototype with small footprint and feasible coupling with optical waveguides could provide additional flexibility for strain analysis in a wide range of fields.

We proposed and demonstrated a gold bowtie-shaped dimer array semi-buried in a deformable polymer substrate. The wavelength tunability of coupled bonding localized surface plasmon resonance modes with different polarizations was confirmed by stretching simulations and experiments. The tuning operations were reconfigurable and reliable under applied elongations of up to 50%.

We propose the design and working principle of a plasmonic concentric compound lens (CCL) comprising inner circular nanoslits and outer circular nanogrooves. Dual-wavelength operations have been achieved for 650 and 750 nm at nanoscale and microscale focal lengths along with their depth of focus (DOF). By tuning the arrangement of nanogrooves, the axial resolution can be modulated and the narrowest DOF is achieved by a design of gradually decreasing groove width. For the ultrahigh tunability of axial resolution, DOF over 400 nm for both working wavelengths is also achieved. We not only developed an approximate-perturbed-focus model for explaining the performance of DOF but also found an extraordinary way to improve the resolution. The enhanced resonance of central disk as nannoantenna in CCL also has great influence on nanofocusing with different deigns of outer nanogrooves. This work provides new sight of focusing ability governed by the general optical nanogrooves. The optimized CCL shows excellent focu...

By integrating silver nanodisks with plasmonic surface lattice resonance, a large-area MoS2 monolayer buried in polydimethylsiloxane substrate can show over 7-fold photoluminescence enhancement. This enhancement is quite stable even under different applied stretching strains.

C.-Y.K. and C.-H.L. contributed equally to this work. This publication was financially supported by the Ministry of Science and Technology, Taiwan (MOST) (107-2221-E-009-113-MY3), the King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) (OSR-2016-CRG5-3005), the KAUST Solar Center, KAUST Catalysis Center, and KAUST baseline funding. The authors would like to thank Prof. Nakamura Shuji of University of California, Santa Barbara and Dr. Lin Chien-Chung of the Industrial Technology Research Institute, Taiwan for the helpful discussion, and express sincere gratitude to Everlight Electronics for helpful technical support with the LED devices.

We have studied the characteristics of frequency response at 850-nm GaAs high-speed vertical-cavity surface-emitting lasers (VCSELs) with different kinds of oxide aperture sizes and cavity length using the PICS3D simulation program. Using 5-μm oxide aperture sizes, the frequency response behavior can be improved from 18.4 GHz and 15.5 GHz to 21.2 GHz and 19 GHz in a maximum of 3 dB at 25 °C and 85 °C, respectively. Numerical simulation results also suggest that the frequency response performances improved from 21.2 GHz and 19 GHz to 30.5 GHz and 24.5 GHz in a maximum of 3 dB at 25 °C and 85 °C due to the reduction of cavity length from 3λ/2 to λ/2. Consequently, the high-speed VCSEL devices were fabricated on a modified structure and exhibited 50-Gb/s data rate at 85 °C.

To realize high-efficiency, AlGaN-based, deep-ultraviolet light-emitting diodes (DUV-LEDs), enhancing their light-extraction efficiency and reducing thermal resistance is very crucial. We proposed a liquid packaging structure that could enhance optical power by 27.2% and 70.7% for flat type and lens type 281-nm DUV-LEDs, respectively. A significant improvement effect at different wavelengths, such as 268 nm and 310 nm, was also observed. Furthermore, using the liquid packaging structure, the thermal resistance was reduced by 30.3% compared to the conventional structure. Finally, the reliability of liquid packaging DUV-LEDs was tested. The light output maintenance of liquid packaging DUV-LEDs was compared to the conventional structure.

A novel plasmonic mirror-image nanoepsilon (MINE) structure is studied to achieve significantly enhanced and localized near-field. It is well-known that the nanorod dimer is able to gain a high local field at the center of the structure by adjusting its rod width, rod length, and gap distance. When adopting an auxiliary nanoring structure electron reservoirs surrounding the nanorod-dimer to form the MINE structure, the local field can be further enhanced owing to a large amount of charges into sharp dimer structure which can confine the accumulation of charges to apexes. Thus, better synergistic interaction of gap effect and lightning-rod effect can be achieved for high field enhancement around nanoscale gap. The symmetric mode in the MINE structure enables strong near-field with a concentrated distribution around the gap. The influences of rod-tip angle and gap distance on the optical properties of plasmonic MINE structures are numerically investigated. With reducing the rod-tip angle and gap distance, considerable enhancements on the field intensities at the rod tips and the gap center can be attributed to the improved lightning-rod and gap effects. The near-field intensities at the rod tip and gap center are dramatically enlarged ~1.94 × 104 and ~1.41 × 104 times with the rod-tip angle of 41° and gap distance of 10 nm, and the near-field is localized within an extremely small range. These features are very beneficial for various plasmonic applications.

Localized surface plasmon resonance (LSPR) with a sharp field gradient and extremely strong field intensity is very attractive for near-field optical nano-tweezers manipulating tiny bio-objects with sizes ranging from sub-10 nm to micrometers. To lower the power consumption of optical trapping and improve the accessibility of LSPR for the targets, we propose and study a plasmonic bowtie notch design with assisted periodic curved grooves. By generating and coupling extra surface plasmon polariton waves into the LSPR, the presented design herein can significantly reduce the required power consumption in experiments for stably trapping single and multiple polystyrene spheres. We believe the idea and results presented in this paper would be helpful in realizing highly efficient nano-tweezers in the plasmonic circuit on-chip.

Red-green-blue (RGB) full-color micro light-emitting diodes (μ-LEDs) fabricated from semipolar (20-21) wafers, with a quantum-dot photoresist color-conversion layer, were demonstrated. The semipolar (20-21) InGaN/GaN μ-LEDs were fabricated on large (4 in.) patterned sapphire substrates by orientation-controlled epitaxy. The semipolar μ-LEDs showed a 3.2 nm peak wavelength shift and a 14.7% efficiency droop under 200 A / cm 2 injected current density, indicating significant amelioration of the quantum-confined Stark effect. Because of the semipolar μ-LEDs’ emission-wavelength stability, the RGB pixel showed little color shift with current density and achieved a wide color gamut (114.4% NTSC space and 85.4% Rec. 2020).