Abstract About twenty years ago, in the autumn of 1996, first white light‐emitting diodes (LEDs) were offered for sale. These then‐new devices ushered a new era lighting by displacing lower‐efficiency conventional light sources including Edison's venerable incandescent lamp as well Hg‐discharge‐based fluorescent lamp. We review history conception, improvement, and commercialization LED. Early models LEDs already exceeded efficiency low‐wattage lamps, extraordinary progress has been made...

While the demand for deep ultraviolet (DUV) light sources is rapidly growing, efficiency of current AlGaN-based DUV light-emitting diodes (LEDs) remains very low due to their fundamentally limited light-extraction (LEE), calling a novel LEE-enhancing approach deliver real breakthrough. Here, we propose sidewall emission-enhanced (SEE) LEDs having multiple mesa stripes utilize inherently strong transverse-magnetic polarized from AlGaN active region and three-dimensional reflectors between...

We demonstrated AlGaN-based deep ultraviolet light-emitting diodes (DUV LEDs) with periodic air-voids-incorporated nanoscale patterns enabled by nanosphere lithography and epitaxial lateral overgrowth (ELO) on a 4-in. sapphire substrate. The ELO improved the crystal quality of overgrown layers at relatively low growth temperature 1050 °C small coalescence thickness less than 2 μm. light output power DUV LED was enhanced significantly 67% an injection current 20 mA. attribute such remarkable...

Fundamental limitations of wide-bandgap semiconductor devices are caused by systematic trends the electron and hole effective mass, dopant ionization energy, carrier drift mobility as semiconductor's bandgap energy increases. We show that when transitioning from narrow-bandgap to semiconductors transport properties charge carriers in pn junctions become increasingly asymmetric characterized poor p-type transport. As a result, demonstration viable based on bipolar transport, such junction...

Fluorescent labeling allows for imaging and tracking of vesicles down to single-particle level. Among several options introduce fluorescence, staining lipid membranes with lipophilic dyes provides a straightforward approach without interfering vesicle content. However, incorporating molecules into in an aqueous solution is generally not efficient because their low water solubility. Here, we describe simple, fast (<30 min), highly effective procedure fluorescent including natural...

AlxGa1−xN/GaN superlattice electron blocking layers (EBLs) with gradually decreasing Al composition toward the p-type GaN layer are introduced to GaInN-based high-power light-emitting diodes (LEDs). GaInN/GaN multiple quantum well LEDs 5- and 9-period Al-composition-graded EBL show comparable operating voltage, higher efficiency as less droop than having conventional bulk AlGaN EBL, which is attributed doping effect, enhanced hole injection into active region, reduced potential drop in by...

Abstract While there is an urgent need for semiconductor-based efficient deep ultraviolet (DUV) sources, the efficiency of AlGaN DUV light-emitting diodes (LEDs) remains very low because extraction photons significantly limited by intrinsic material properties AlGaN. Here, we present elegant approach based on a LED having multiple mesa stripes whose inclined sidewalls are covered MgF 2 /Al omni-directional mirror to take advantage strongly anisotropic transverse-magnetic polarized emission...

Despite a rapidly growing demand for efficient man-made deep-ultraviolet (DUV) light sources, widespread adoption of AlGaN-based DUV light-emitting diodes (LEDs) is currently obstructed by extremely poor extraction photons due to the intrinsic material properties AlGaN active region. Here, we present 280 nm LEDs having arrays truncated cone (TC)-shaped mesas coated with MgF2/Al reflectors on inclined sidewalls effectively extract intrinsically strong transverse-magnetic-polarized emission....

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Threshold voltage (VTh) drift of Schottky-type p-GaN gate high-electron mobility transistor (HEMT) was analyzed under high-voltage and hard switching conditions with a resistive load (R-Load). To overcome the distortion in drain current (ID) – (VG) curve caused by internal capacitance (IDisp) charging during transients, method is presented to accurately measure dynamic VTh through appropriate correction IDisp. The variation tracked gate-drive rise/fall times 200 ns. During operation,...

Indium tin oxide (ITO) thin films deposited using the oblique angle deposition (OAD) technique exhibit a strong correlation between structural and optical properties, especially bandgap energy. The microstructural properties of ITO are strongly influenced by tilt used during OAD process. When changing angle, refractive index, porosity, energy also change due to existence preferential growth direction at interface substrate. Experiments reveal that film's varies from 3.98 eV (at normal...

A genetic algorithm is employed to find an optimum epitaxial structure of multiple quantum wells (MQWs) and electron-blocking layer (EBL) for a GaInN-based light-emitting diode (LED). The optimized LED composed locally Si-doped barriers (QBs) in the MQWs quaternary heterostructured AlGaInN EBL having polarization-induced electric field directed oppositely that conventional AlGaN EBL. shows 15.6% higher internal efficiency, 24.6% smaller efficiency droop, 0.21 V lower forward voltage at 200...

The temperature-dependent external quantum efficiencies (EQEs) were investigated for a 620 nm AlGaInP red light-emitting diodes (LEDs), 450 GaInN blue LED, and 285 AlGaN deep-ultraviolet (DUV) LED. We observed distinct differences in the variation of EQE with temperature current density three types LEDs. Whereas LED increases as decreases below room temperature, EQEs DUV LEDs decrease same change low-current regime. free carrier concentration, determined from dopant ionization energy, shows...

Two novel, CN-substituted <italic>ortho</italic>-terphenyl (OTP) core based bipolar type host materials were designed and synthesized for application in blue thermally activated delayed fluorescence (TADF) devices.

The efficiency of Ga0.87In0.13N/GaN single and multiple quantum well (QW) light-emitting diodes is investigated under photoluminescence (PL) electroluminescence (EL) excitation. By measuring the laser spot area (knife-edge method) absorbance GaInN QW (transmittance/reflectance measurements), PL excitation density can be converted to an equivalent EL density. droop-onset occurs at 2.08 × 1026 cm–3 s–1 (J = 10 A/cm2), whereas no droop found for densities as high 3.11 1027 149 A/cm2)....

In this paper, the crystallization behavior of nitrogen‐doped SbSe films was investigated as a function nitrogen content. We found that SET resistance and temperature were higher than those un‐doped films. Moreover, crystallinity average grain area decreased with increasing content because formation nitrides, which disturbed crystal growth. Theoretical modeling conducted to verify effects doping, results in good agreement experimental results. Through optical band gap measurement, we doping...

Wafer level transient voltage measurement (WLTVM) to estimate the short circuit capability of AlGaN/GaN HEMT devices is suggested. Two groups samples with similar DC and switching properties but different capabilities 4-7 > 10μs were evaluated. The extracted junction temperature measured saturation/linear current under repeated stresses suggest that failure attributed degradation in drift region. WLTVM could measure potential change along region during condition. sample lower short-circuit...

The effect of strongly-imbalanced carrier concentration and mobility on efficiency droop is studied by comparing the onset voltage high injection, current density droop, magnitude as well their temperature dependence, GaInN-based blue green light-emitting diodes (LEDs). An n-to-p asymmetry factor defined σn/σp, was found to be 17.1 for LEDs 50.1 LEDs. Green LEDs, when compared were shown enter high-injection regime at a lower voltage, which attributed less favorable p-type transport...

Abstract Membrane‐bound vesicles such as extracellular (EVs) can function biochemical effectors on target cells. Docking of the onto recipient plasma membranes depends their interaction with cell‐surface proteins, but a generalizable technique that quantitatively observe these vesicle–protein interactions (VPIs) is lacking. Here, we describe fluorescence microscopy measures VPIs between single and either in surface‐tethered or membrane‐embedded state. By employing cell‐derived (CDVs)...

Smallpox, a disease caused by the variola virus, is one of most dangerous diseases and had killed numerous people before it was eradicated in 1980. However, smallpox has emerged as threatening bio-terrorism agent; first- second-generation vaccines have been controversial severe adverse reactions, new demands for safe raised some attenuated developed. We developed cell culture-based highly third-generation vaccine candidate KVAC103 strain 103 serial passages Lancy-Vaxina derived from Lister...

This work reports the transient measurement of AlGaN/GaN high electron-mobility transistor (HEMT) drift region potential in power state during switching. The effect stress has been reported by device characterization after or DC at voltages below operating to avoid failure. However, is challenging, since can sustain only for a few μs before failure occurs. In this work, test structure with voltage probe inserted between gate and drain used perform real-time voltages. It found that electric...

A hendecafacet (HF) microsized light emitter based on an InGaN/GaN multiple quantum well (MQW) is grown via selective area metal–organic chemical vapor deposition. The HF found to possess four crystallographic facets, (0001), {11̅01}, {112̅2}, and {11–20}. Distinct facet-dependent emission properties, investigated by confocal scanning photoluminescence (PL) cathodoluminescence (CL) measurements, are originate from differences in indium composition InGaN thickness of the MQW. Facet-dependent...

This work investigates the effect of N2O plasma treatment on reliability p-GaN gate AlGaN/GaN high-electron-mobility transistors (HEMTs), specifically in AlGaN drift region. The formation a GaON/AlON compound layer surface after was confirmed by energy-dispersive x-ray spectroscopy mapping and photoelectron analysis. When device is under highly stressed conditions, reduces number negatively charged interface traps protects hindering Ga-out diffusion. high temperature reverse bias test...