Realization of efficient yellow-light-emitting diodes (LEDs) has always been a challenge in solid-state lighting. Great effort made, but only slight advancements have occurred the past few decades. After comprehensive work on InGaN-based yellow LEDs Si substrate, we successfully made breakthrough and pushed wall-plug efficiency 565-nm-yellow to 24.3% at 20  A/cm2 33.7% 3  A/cm2. The success can be credited improved material quality reduced compressive strain InGaN quantum wells by...

GaN/InGaN light emitting diodes (LEDs) grown on sapphire substrates have current transport along the lateral direction due to insulating nature of substrate. The finite resistance n-type GaN buffer layer causes pn junction be nonuniform and “crowd” near edge contact. current-crowding effect is analyzed both theoretically experimentally for p-side-up mesa structure LEDs. calculation yields an exponential decay distribution under p-type contact with a characteristic spreading length, Ls. It...

A laboratory fire-extinguishing system was applied to investigate the effect of gas-liquid ratio on performance aqueous film-forming foam (AFFF) in diesel pool fire, and proposed mechanism AFFF is carefully analyzed. The results show that possesses shortest extinguishing time 42s lowest liquid consumption 210 g at a 16, exhibiting best performance. Chemical analysis indicates proper beneficial enhance expansion drainage rate affect cooling covering effects foam, thus achieving optimum...

We proposed a flexible and mask-less approach to directly fabricate patterned red phosphor layer on Y3Al5O12:Ce3+ (YAG:Ce3+) phosphor-in-glass (PiG) for high-power white light-emitting diodes (WLEDs). This was realized by ultraviolet (UV) assisted initiative cooling based water condensing. A low-temperature precursor glass matrix with high refractive index synthesized the YAG:Ce3+ PiG. By controlling UV pre-curing time, micro-concaves adjustable sizes were fabricated embedded UV-curable...

Microlens arrays (MLAs) have attracted wide attention due to their crucial applications in optics, optoelectronics, and biochemistry. In this paper, we present a simple green approach for the economical fabrication of MLAs with controlled curvature based on water condensing. By controlling input current working time initiative cooling viscoelasticity UV-curable polymer, uniform porous films adjustable morphology were prepared. aspect ratios 1.41, 1.01, 0.69 fabricated by micromolding film...

All-inorganic color converters are promising luminescent materials for high-power white lighting due to their excellent heat resistance and high thermal conductivity. However, the low rendering of limits applications in high-quality lighting. Herein, a broad-band stable phosphor-in-glass (PiG) was developed light-emitting diodes (WLEDs). This PiG converter fabricated by sintering green/red phosphor glass film on plate with patterned metal layer. The green Y3Al3.08Ga1.92O12:Ce3+ has broad...

Thermal management is a key issue for high-power light-emitting diodes (LEDs). In this study, novel packaging structure was proposed to reduce the die-bonding interface thermal resistance and provided new idea LED heat-dissipation. The chip embedded into square groove at lead-frame substrate. gap between edges of filled with boron nitride/silicone composite. So heat generated from could be dissipated side surfaces experimental results show that heat-dissipation ability LEDs has been...

This paper studies the macroeconomic consequences of selected information supply by news media. We document empirically that media's reporting business is concentrated, particularly among largest firms. News coverage associated with higher likelihood obtaining financing, investment, and greater profitability. In a quantitative model media sector matches these facts, alleviates asymmetric in financial markets for reported However, concentrates on large firms who are not financially...

Advanced lens fabricating techniques are urgently required for the development of light-emitting diode (LED) packaging. In this study, a method LED lenses was proposed based on electrohydrodynamics (EHD). lenses, normal stress air–liquid interface induced and adjusted by an electric field applied around liquid material. By controlling stress, could be tailored into desired morphologies. Three kinds typical morphologies, namely cone, ellipse asymmetric, were fabricated varying type. Moreover,...

A simple and low-cost method for fabricating lens with large view angle was proposed based on droplet evaporation high-power light-emitting diodes (LEDs). In such a method, an immiscible vaporizable deposited the top surface of liquid silicone lens. By applying heat load, cured evaporated simultaneously. Then, lenses craters were fabricated view-angle emission LEDs. experiments, diameter depth crater controlled by adjusting volume droplet. As result variation carter size, light intensity...

In this work, the optical performance of chip-scale packaged (CSP) white light-emitting diodes (LEDs) was enhanced by a phosphor-in-glass (PiG) converter with high-reflective dam. The dam consisted boron nitride (BN)/silicone composite fabricated at side wall LED chip and PiG to obtain PiG-BN-CSP LED. optimized adjusting concentration BN particles. When is 7.5 wt%, PiG-7.5BN-CSP achieves an appropriate natural light. related luminous efficiency (LE), correlated color temperature (CCT),...

Microlens arrays (MLAs), as one of the key features in optoelectronics field, have attracted a lot attention recently. Unfortunately, existing fabrication methods MLAs many disadvantages, such complex procedures and difficult morphology control. This paper presents low-cost tunable approach for concave on ultraviolet (UV) polymer surfaces. We used condensed water droplets, formed by initiative cooling, template formation this approach. A sacrificial layer material was introduced to fabricate...

In this study, a simple and low-cost method is proposed to enhance angular color uniformity (ACU) of color-mixed light-emitting diodes (cm-LEDs) by introducing diffuse coating layer. Optical models the cm-LEDs packaging modules were constructed Monte Carlo ray-tracing simulation. The simulation results demonstrate ACU enhancement with application layer on reflection cup. Owing strong light scattering effects layer, different emitted from chip are sufficiently mixed. was fabricated spraying...

The paper presents an analysis of self-heating effect on micro-machined temperature difference air flow sensor, and demonstrates through modeling simulation that can influence the output sensor. mathematical model sensor based existing microsensor chip is set up, some details structure are considered in model. sensor's distribution with respect to rate computed by coupling heat transfer interaction between fluid using ANSYS Fluent. effects two measuring thermistors studied respectively order...

Thermal management is a key issue for high-power light-emitting diodes (LEDs). Reducing the die-bonding interface thermal resistance one of most important issues management. In this study, novel packaging structure was proposed to reduce resistance. The LED chip embedded into square groove at lead-frame substrate and gap between edges filled with boron nitride (BN)/silicone composite. So heat generated from could be dissipated side surfaces substrate, heat-dissipation area increased. results...

In this paper, the analysis of air contaminant's influence on measurement reliability hot-film flow sensor is presented. Modeling particles' motion states and temperature distribution using ANSYS Workbench's Fluent module are carried out. The structure details chip included in finite element model for computing. with respect to rate contaminant ignored analyzed at first. Then field consideration simulated order analyze contaminant. particle diameter dusts content two key parameters involved...

The microchannel heat sink has been recognized as an excellent solution in high-density flux devices for its high efficiency removal with limited spaces; however, the most effective structure of microchannels dissipation is still unknown. In this study, fluid flow and transfer high-temperature wavy various shaped fins, including bare channel, channel circular, square, diamond-shaped are numerically investigated. liquid metal-cooled characteristics proposed compared that smooth straight...

I study the transmission of financial shocks using an estimated heterogeneous firm model. Following a contractionary shock, financially constrained firms cut investment, but unconstrained increase investment due to lower capital price and interest rate. After matching empirical dynamics prices elasticity find limited role firms’ response in dampening aggregate decline. Nonfinancial adjustment friction is key generating this result. Without friction, becomes unrealistically sensitive prices,...

Microchannel heat sink is widely applied in high-density flux devices for its high efficiency dissipation. However, the most effective geometrical configuration of microchannels best transfer augmentation with least pump power penalty still unknown. In this research, a microchannel different shaped periodic reentrant cavities on channel sidewalls are numerically studied. Three kinds structures introduced, including convex quarter-circular, concave and inclined cavities. The comprehensive...

A two-step removing GaAs substrate technique by using HNO3 solution is reported. In the authors’ experiments, as compared with other ratios, etch rate of HNO3:H2O2:H2O=1:6:1 faster. addition, etched surface nitric acid has about 0.15 μm smoothness. The high selectivity HNO3:H2O2:H2O=1:4:1 for GaAs/GaInP demonstrated smooth morphology whose roughness 4.57 nm. advantages this are easy, repeatable, and no contamination. It a very useful process in light-emitting diode fabrication.

It is very important to increase light extraction efficiency in LED structure design. The antireflection film technology a simple and cost-cutting method. In this paper, we proposed SiON layer as an coating deposited on the surface of conventional AlGaInP which can be used improve performance chip. LED, ITO thin was current spreading layer. propagation lights through these layers analyzed by transfer matrix thicknesses have been optimized. PECVD. results experiments showed that optical power...

This paper identifies the aggregate financial shocks and quantifies their effects on business investment based an estimated DSGE model with firm-level heterogeneity. On average, contribute only 1.1% of variation in U.S. public firms' investment. The negligible relevance mainly results from interaction between heterogeneity general equilibrium effects. Following a contractionary shock, financially constrained firms are directly forced to cut investment, which dampens demand lowers capital...