Recessed-gate AlGaN/GaN MISHEMTs are promising candidates for power electronics but often suffer from interface defects introduced during gate recessing, which degrade device performance and reliability. In this work, a supercritical fluid nitrogen passivation (SCFNP) technique is developed to address this limitation. The process is carried out at 180 °C under high pressure and enables efficient defect repair at both the Al2O3/AlGaN interface and the recessed-gate surface. Devices treated with SCFNP exhibited significantly improved electrical performance, including a positive threshold voltage (V TH) shift to +2.2 V (extracted at I D = 1 mA/mm), an increased maximum drain current of 600 mA/mm, a substantially reduced gate leakage current of 9.9 × 10-8 mA/mm, and a high on/off current ratio of 5.0 × 109. The gate leakage current decreased by nearly 2 orders of magnitude, while the OFF-state breakdown voltage (BV) increased by 27.8% (from 557 to 712 V). Dynamic on-resistance (R ON) measurements further revealed a 25.6% reduction in current collapse under high-voltage stress. TCAD simulations corroborate these experimental results by demonstrating that reduced interface trap density suppresses peak electric fields at the drain edge, thereby validating the observed BV enhancement mechanism. Overall, SCFNP represents a low-temperature and scalable postfabrication passivation strategy for reliable GaN power devices.

We present a plane-convex open microcavity that enables room-temperature polariton spectroscopy with a simple geometric handle on the coupling rate. The effective length Leff is absolutely calibrated from the free-spectral range, and piezo tuning is performed at near-normal incidence (k∥≈0) to avoid angle-induced degradation. Using spin-coated PEA2PbI4 quasi-2D perovskites, we observe clear anti-crossings in reflection, with vacuum Rabi splittings up to 79 meV (reflection) and 84 meV (PL) near Leff≈3.4 μm. A linewidth-corrected analysis converts the apparent splitting into the coherent exciton-photon coupling rate g, revealing a robust geometric scaling g∝Leff-1/2 across multiple longitudinal orders and spatial sites, consistent with the filled-mode thin-film limit where transverse area cancels in the mode volume. The platform establishes a compact, broadly compatible testbed for room-temperature polaritons and provides a practical design rule: shortening Leff is a reliable, geometric lever to strengthen collective coupling in plane-convex microcavities.

Electroluminescent (EL) devices consisting of a single metal-semiconductor contact and a gate effect structure have garnered significant attention in the field of perovskite light-emitting devices. This interest is largely due to the thermal stability of the active layer and the simplicity of the device structure. However, the application of these devices in large-area light-emitting applications is hindered by the inherently low carrier mobility in perovskite materials. In our study, we addressed this limitation by optimizing the nanostructure within the electrodes, which resulted in enhanced electroluminescence and linear polarization. To confirm the luminescence mechanism and the observed enhancement, we conducted comprehensive electrical and optical characterization studies. These characterization studies demonstrated the effectiveness of our approach in improving the performance of perovskite-based EL devices, paving the way for their broader application in large-area light-emitting technologies.

Optical modulators are indispensable components in optical communication systems and must be designed to minimize insertion loss, reduce driving voltage, and enhance linearity. State-of-the-art silicon modulator technology has limitations in terms of power, performance, and spatial size. The addition of materials such as thin-film lithium niobate (TFLN), silicon–organic hybrids (SOH), and plasma–organic hybrids (POH) has improved the modulation performance in silicon photonics. An evaluation of the differences among these modulators and their respective performance characteristics is conducted.

The objective of this study is to optimize the trade-off between threshold voltage (VTH) and maximum drain current (ID,max) in recessed gate AlGaN/GaN metal insulator semiconductor high electron mobility transistor (MISHEMT) using atomic layer etching (ALE) technology, with technical computer-aided design (TCAD) simulations assisting in the analysis of the underlying mechanisms to demonstrate the high performance and reliability of GaN-based power application. A normally-off recessed gate MISHEMT with varying AlGaN remaining thickness (2 nm, 3 nm, and 5 nm) was fabricated using the ALE process, ensuring precise etch depth and minimal surface damage. The device with a 5 nm AlGaN remaining thickness exhibited excellent performance, with an ID,max current of 347 mA mm-1, a VTH of +2.6 V, and a breakdown voltage (BV) of 830 V, compared to the AlGaN barrier with remaining thicknesses of 3 nm and 2 nm, which only reached 120 V and 75 V, respectively. The different recessed gate AlGaN remaining electric field distribution results were verified according to TCAD simulations. This is attributed to the hot electrons effect under the action of the high electric field to promote electrons to overcome potential energy barriers that are injected into a buffer, barrier, or insulating layers and trapped there, degrading off-state BV capability.

Silicon photonics, merging silicon-based electronics and photonics, offers a transformative leap in optical technologies by providing high-density, high-speed optical interconnects at reduced costs. Central to this progress is the silicon nitride (Si3N4) waveguide, recognized for its low propagation losses and compatibility with CMOS manufacturing processes, enabling photonic-electronic integration on a single chip. This paper addresses the critical challenge of cost-efficient packaging in silicon photonics through the direct vertical bonding of photonic-crystal surface-emitting lasers (PCSELs) onto Si3N4 grating couplers. PCSELs, known for their high power, coherent vertical emission, and superior beam quality, are optimized here for integration with silicon photonics. This study employs an adjoint shape optimization algorithm to design an inverse-designed vertical grating coupler (VGC) to improve coupling efficiency. Our approach demonstrates significant advancement by achieving a coupling efficiency of 84.4% (-0.74 dB) for the inverse-designed VGC and 75.1% (-1.24 dB) for the combined metagrating and forward-designed grating coupler with direct PCSEL bonding. This efficiency is achieved through meticulous design and optimization of the PCSEL structure, grating coupler parameters, and incorporating a distributed Bragg reflector (DBR) to minimize losses. These findings showcase the potential for high-performance, cost-effective silicon photonic devices, setting a new benchmark for integrated photonic systems. This work presents a holistic and innovative solution, addressing the key challenges in the field and paving the way for future commercialization and broader silicon photonics applications.

2D monolayered transition-metal dichalcogenides (TMDCs) are promising materials for realizing ultracompact, low-threshold semiconductor lasers. And the development of the electrical-driven TMDC devices is crucial for enhancing the integration potential of practical optoelectronic systems. However, at the current stage, the electrically-driven 2-D TMDC laser has never been realized. Herein, the first electrically-driven 2-D TMDC microcavity laser have been developed. In this device, an alternating current (AC) generates electroluminescence lasing in suspended monolayered WSe2 integrated on a microdisk cavity. The input-output curve, bandwidth narrowing, and second-order coherence is analyzed to confirm the lasing characteristics at room temperature. The realization of the room-temperature AC-driven 2-D TMDC laser establishes a new area of research on electrically pumped compact lasers and is likely to assist with the implementation of diverse TMDC-based practical photonic devices in the future.

We have developed an open microcavity system with an electrically tunable cavity length. In its current plano-cavity configuration, we have achieved a $1.2\ \mu\mathrm{m}$ cavity length, corresponding to a free spectral range (FSR) of approximately 140 nm. This offers a universal platform to explore strong light-matter coupling with various materials in microcavity systems. Preliminary results indicate an anti-crossing pattern characteristic of the strong coupling regime, with a measured Rabi splitting of approximately 0.1 eV.

Two-dimensional (2-D) monolayer transition-metal dichalcogenides (TMDCs) are promising materials for realizing ultracompact, low-threshold semiconductor lasers. And the development of the electrical-driven TMDC devices is crucial for enhancing the integration potential of practical optoelectronic systems. However, at current stage, the electrically-driven 2-D TMDC laser has never been realized. Herein, we have developed the first electrically-driven 2-D TMDC microcavity laser.

In this research, we introduce an advanced methodology for the calculation of bulk light sources tailored for free-form surface design, focusing on the principle of energy conservation. This method is especially relevant for the evolving needs of micro-LED packaging, highlighting its potential in this burgeoning field. Our work includes the development of an algorithm for creating Freeform-Designed Chip-Scale Package (FDCSP) components. These components seamlessly integrate LEDs and lenses, underscoring our commitment to advancing free-form surface design in chip-level packaging. By adhering to the principle of energy conservation, our approach facilitates a meticulous comparison of simulation outcomes with predefined target functions. This enables the iterative correction of discrepancies, employing layering techniques to refine the design until the simulated results closely align with our goals, as demonstrated by an appropriate difference curve. The practical application of these simulations leads to the innovative design of FDCSP devices. Notably, these devices are not just suitable for traditional applications in backlight modules but are explicitly optimized for the emerging sector of micro-LED packaging. Our successful demonstration of these FDCSP devices within backlight modules represents a significant achievement. It underscores the effectiveness of our design strategy and its expansive potential to transform micro-LED packaging solutions. This research not only contributes to the theoretical understanding of energy conservation in lighting design but also paves the way for groundbreaking applications in micro-LED and backlight module technologies.

To enhance the interaction between electromagnetic fields and reduce photoluminescence (PL) lifetime in plasmon-enhanced fluorescence, this study presents a novel approach involving the fabrication of gold (Au) nanohole arrays (ANA) decorated with ring-shaped silver nanoparticles (AgNPs) on a silicon-dioxide (SiO2)/silver (Ag) substrate. The surface plasmon resonance coupling in terms of the PL reactions of ANA substrates with and without ring-shaped AgNPs is investigated via experiments and numerical simulations. The remarkable enhancement of PL intensity of the proposed substrate is attributed to increased absorption, which enables the tuning of surface-enhanced electromagnetic fields. Specifically, the Raman signal of rhodamine 6G (R6G) dye and the PL intensity of 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) molecules are significantly enhanced 3.7 and 2.2 times, respectively, compared to those of the bare ANA substrate. Meanwhile, the PL lifetime is reduced by 46.15%. These results confirm that ANAs decorated with ring-shaped AgNPs can significantly improve plasmon-enhanced fluorescence. The findings presented herein demonstrate the potential to revolutionize biosensing, imaging, and photonics.

In this study, we propose a novel high-concentration photovoltaic (HCPV) cell by considering both the light leakage characteristics of the Fresnel-lens-based solar cell modules and the performance issues arising from cloud shading in practical use. We use our self-constructed systems to conduct field measurements for up to half a year under various environmental conditions. According to the acquired results, it was surprising to know that in the area other than the focusing area, the so-called light leakage region, there always bears illuminance of about 20,000–40,000 lx whether it is a sunny day or a cloudy day with different cloud conditions. Such an interesting result is caused by the light scattering of the clouds and the inherent leakage characteristic of a Fresnel lens. To prove this important finding, we simulated the illuminance of the Fresnel lens structure used in the measurement with apertures of different sizes to determine the detected area. In the laboratory, the diffuse plates were used to mimic the situation of varying cloud layer thicknesses. The trend of calculated and measured results fitted well with the field measurements. Also, the experimental and simulation results show that the round angle and draft facet of the Fresnel lens were responsible for light leakage. This finding prompted us to propose a hybrid high-concentration solar module in which more cost-effective polycrystalline silicon solar cells are placed around the high-efficiency wafer of HCPV to capture the dissipated light leakage and convert it into usable electricity.

Dynamic behaviors for light emission of one- and two-photon excitation in single crystalline perovskite bulks with metallic and dielectric-nanoparticles hybrid configurations are experimentally examined. Thereby, a series of comprehensive simulations are conducted for investigating the feasible mechanism and the relevant interactions in such sophisticated configurations. Under one-photon excitation, optical pumping fluences can only irradiate and penetrate in the skin depths of single crystalline perovskite-nanoparticle hybrid configurations; therefore, the corresponding light-emitting performance of hybrid configuration mixed with Au NPs can be ameliorated due to a stronger scattering field of Au NPs than that of SiO2 NPs. On the other hand, under two-photon excitation, optical pumping fluences can irradiate and penetrate much deeper; hence, the corresponding light-emitting performance of hybrid configurations mixed with both Au NPs and SiO2 NPs can be improved. However, owing to the shadowing effect of Au NPs, optical pumping fluences and the corresponding light-emitting in the interior regions will be shielded. Consequently, the overall light-emitting performance is slightly lower than that mixed with SiO2 NPs. We investigate the feasible mechanism in such sophisticated configurations and identify the relevant interactions between NPs and MAPbBr3 perovskite material, providing proper interpretations for a deeper understanding of the dynamic behaviors of one- and two-photon light emission in such single crystalline perovskite-nanoparticle hybrid configurations, paving a new route in nonlinear optics.

The photodeposition of metallic nanostructures onto ferroelectric surfaces could enable new applications based on the assembly of molecules and patterning local surface reactivity by enhancing surface field intensity. DCJTB (4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran) is an excellent fluorescent dye and dopant material with a high quantum efficiency used for OLED displays on the market. However, how to raise the photoluminescence (PL) and reduce the lifetime of DCJTB in a substrate remain extraordinary challenges for its application. Here, we demonstrate a tunable ferroelectric lithography plasmon-enhanced substrate to generate photo-reduced silver nanoparticles (AgNPs) and achieve enhanced PL with a shortened lifetime depending on the substrate's annealing time. The enhanced PL with shortened lifetimes can attribute to the localized electromagnetic (EM) wave produced by the nanotextured AgNPs layers' surface and gap plasmon resonances. The simulation is based on the three-dimensional finite element method to explain the mechanism of experimental results. Since the absorption increases, the remarkable enhanced PL of DCJTB can attain in the fabricated periodically proton exchanged (PPE) lithium niobate (LiNbO3) substrate. Furthermore, the proposed fabrication method demonstrates to help tune the surface EM wave distribution in the substrate, which can simultaneously achieve the significantly shortened lifetime and high PL intensity of DCJTB in the substrate. Compared with the un-annealed substrate, the PL intensity of DCJTB in the assembly metallic nanostructures is enhanced 13.70 times, and the PL's lifetime is reduced by 12.50%, respectively. Thus, the fabricated substrate can be a promising candidate, verifying chemically patterned ferroelectrics' satisfaction as a PL-active substrate.

The authors wish to make following corrections in this paper [...].

In this study, we investigated the characteristic difference between the two different configurations of the three-dimensional shell–core nanorod LED. We achieve a degree of polarization of 0.545 for tip-free core–shell nanorod LED and 0.188 for tip core–shell nanorod LED by combining the three-dimensional (3D) structure LED with photonic crystal. The ability of low symmetric modes generated by photonic crystals to enhance degree of polarization has been demonstrated through simulations of photonic crystals. In addition, light confinement in GaN-based nanorod structures is induced by total internal reflection at the GaN/air interface. The combination of 3D core–shell nanorod LED and photonic crystals cannot only produce a light source with a high degree of polarization, but also a narrow divergence angle up to 56°. These 3D LEDs may pave the way for future novel optoelectronic components.

This work fabricates a plasmonic lithium niobate substrate with metal nanoparticles (MNPs) to enhance electromagnetic field interaction and diminish lifetime with concentration dependence. The enhanced photoluminescence (PL) from dye molecules in lithium niobate substrate and shortened lifetimes associate with plasmon resonance arising from the metal nanoparticles (MNPs) layers. We experimentally and numerically verified that the surface plasmon coupling between MNPs potentially influences PL reactions. The remarkable enhanced PL of deposited MNPs substrate can be achieved by increasing absorption. The fabricated structure can help tune the surface-enhanced electromagnetic field. The Raman signal of rhodamine 6G dye and PL intensity of DCJTB (4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran) molecules in the fabricated substrate are enhanced 13 times and 10.26 times compared to untreated. Besides, the lifetime is reduced by 22.63%. This work is a perspective method for designing a PL-active lithium niobate substrate using photoinduced metal deposition with concentration dependence.

In this work, we will introduce our works on metal halide perovskite thin film random lasers and the latest finding of the enhanced lasing performance via in-situ AgI diffusion in perovskite materials. For the hybrid configuration, optical absorption is found to be evidently increased, indicating the availability of optical pumping fluences is prominently improved. Meanwhile, rugged film morphology and the corresponding chemical reaction are also observed and further investigated. Besides, by conducting a series of temperature-dependent cryogenic and a systematic power-dependent micro-PL measurement with different excitation wavelengths, the relationship in wavelength positions between each other can be validated, confirming the mechanism for the enhancement on light emission performance. Finally, for a such hybrid configuration, the corresponding randomlasing performance is found can be enhanced by a factor of three.