Improvements of the internal quantum efficiency by reduction threading dislocation density and light extraction using UV transparent p-type cladding contact layers, reflecting ohmic contact, chip encapsulation with optimized shape refractive index allowed us to obtain external 10.4% at 20 mA CW current output power up 9.3 mW 278 nm for AlGaN-based deep-ultraviolet light-emitting diodes grown on sapphire substrates.

We report AlGaN deep ultraviolet light-emitting diodes (LEDs) at 250 and 255nm that have short emission wavelengths. For an unpackaged 200×200μm square geometry LED emitting 255nm, we measured a peak power of 0.57mW 1000mA pulsed pump current. similar device 250nm the output 0.16mW was 300mA Progress is based on development high quality cladding layers with Al content up to 72%, which were grown over AlGaN∕AlN superlattice buffer sapphire substrates. These n-Al0.72Ga0.28N doped Si about...

We present the analysis of external quantum efficiency in AlGaN deep ultraviolet (DUV) light-emitting diodes (LEDs) on sapphire substrates and discuss factors affecting output power DUV LEDs. Performance LED is related to optimization device structure design improvements epitaxial material quality.

The semiconductor triboelectric nanogenerator (TENG) based on the tribovoltaic effect has characteristics of direct current and high density, but energy transfer conversion mechanism is not completely clear. Here, a series gallium nitride (GaN)-based direct-current TENGs (SDC-TENGs) are investigated for clarifying carrier excitation transport mechanism. During friction process, external output always flows from GaN to silicon or aluminum, regardless direction built-in electric field, because...

Abstract AlGaN‐based deep ultraviolet light‐emitting diodes (UV LEDs) have gained rapidly growing attention due to their wide applications in water purification, air disinfection, and sensing as well optical communication. Moreover, UV radiation has been verified one of effective way inactivate COVID‐19. However, although numerous efforts made LED chips, the reported highest external quantum efficiency (EQE) them is 20.3%, which far lower than that visible LEDs. The EQE commercial packaged...

Tin dioxide (SnO 2 ) is a widely used electron transport layer (ETL) in perovskite detectors, and optimizing the ETL common strategy to enhance detector performance.

In this letter, we report the pulsed atomic-layer epitaxy of ultrahigh-quality AlN epilayers and AlN/Al0.85Ga0.15N multiple quantum wells (MQWs) on basal plane sapphire substrates. Symmetric asymmetric x-ray diffraction (XRD) measurements room-temperature (RT) photoluminescence (PL) were used to establish ultrahigh structural optical quality. Strong band-edge RT PL at 208 228 nm was obtained from MQWs. These data clearly their suitability for sub-250-nm deep UV emitters.

We report on 245–247 nm AlGaN-based deep ultraviolet (DUV) light-emitting diodes with continuous wave output power up to 2 mW. DUV peak emission wavelength of 245 and 247 exhibit turn-on voltage less than 10 V. At room temperature cw operation the maximum external quantum efficiency was close 0.18%, which is highest value published date for devices shorter 250 nm. A large droop observed at current densities above 100 A/cm2 attributed self-heating, carrier spillover from QWs into barrier...

A strategy to reduce the density of threading dislocations (TDs) in AlN epilayers grown on sapphire substrates is reported. The TDs experience a redirection their line orientation which found coincide with imposed increases both V/III ratio and overall flux rate leading formation an internal subinterface delineated by changes dislocation orientation. Threading either large kinks then redirect into or form dipole half loops via annihilation redirected segments opposite sign latter significant...

Polarization effects have been studied in GaN/AlGaN multiple quantum wells (MQWs) with different c-axis orientation by means of excitation-dependent photoluminescence (PL) analysis. Quantum structures were grown on [0001]-oriented sapphire substrates (C plane) and single-crystalline [11̄00]-oriented freestanding GaN (M using the metalorganic chemical vapor deposition technique. Strong PL spectrum line blueshifts (up to 140 meV) which are correlated excitation intensity obtained for C-plane...

We report on the growth of low-defect thick films AlN and AlGaN trenched AlGaN/sapphire templates using migration enhanced lateral epitaxial overgrowth. Incoherent coalescence-related defects were alleviated by controlling tilt angle fronts allowing Al adatoms sufficient residence time to incorporate at most energetically favorable lattice sites. Deep ultraviolet light emitting diode structures (310nm) deposited over fully coalesced exhibited cw output power 1.6mW 50mA current with...

Lifetime measurements on single-chip, packaged 285 nm light-emitting diodes (LEDs) performed under constant current injection at 20 and 75 mA, were compared to the performance of unbiased LEDs baked equivalent operating junction temperatures. The thermally stressed devices showed a lesser degradation than those electrically stressed, indicating that elevated temperature alone does not cause degradation. Despite decay less half initial power injection, time-resolved photoluminescence active...

We report on deep ultraviolet light emitting diodes using AlGaN multiple quantum well active regions and with peak emission at 280 nm. A new buffer layer region design resulted in flip-chip devices continuous wave powers as high 0.85 mW for a pump current of 20 mA record external efficiency over 1%. The power saturated 5 dc 200 mA.

Using a micro-pixel design, we report the demonstration of high-power deep UV AlGaN-based light-emitting diodes (LEDs) with peak emission wavelength at 280nm. The design comes in response to lateral current crowding problems, which severely limit maximum possible active area and overall performance ordinary square geometry III-nitride LEDs fabricated on insulating substrates. It is shown that interconnected significantly reduces both device series resistance thermal impedance, thereby...

We present a study of reliability AlGaN-based 280nm deep ultraviolet light-emitting diodes on sapphire substrate grown by migration-enhanced metal-organic chemical vapor deposition. Two modes optical power degradation were observed: catastrophic and gradual. The is believed to be due metal alloying at macroscopic defects in the top p layers diode structure. For gradual degradation, two time constants determined, which temperature bias dependent. temperature-dependent part, values activation...

The band-edge excitonic properties of AlN are investigated using low-temperature (1.7K) optical reflectance and transmission measurements samples with various crystal orientations. A, B, C excitons found to have energies 6.025, 6.243, 6.257eV in unstrained material, which shift strain. results compared a calculation exciton oscillator strengths yield crystal-field splitting −230meV AlN, good agreement previous ab initio calculations.

This letter reports on a low thermal impedance flip-chip packaged deep ultraviolet light-emitting diodes emitting at 280 nm featuring finned heat sink. For single 100μm×100μm device onto an AlN submount and mounted TO-66 header with attached sink, total junction to ambient as 33°C∕W was obtained. Numerical simulations of the transfer show that excessive value effective is mostly limited by insufficient area.

We report on AlGaN-based light-emitting diodes over sapphire with peak emission at 280nm. A modified active layer structure consisting of four multiple quantum wells, addition an electron blocking magnesium doped p-AlGaN layer, improved contacts along flip-chip packaging resulted in a cw power 0.7mW 230mA for single 200μm×200μm device. Flip-chipping 100μm×100μm devices parallel configuration the dc saturation current and enabled us to obtain 1.53mW (at 450mA) pulse as high 24mW 1.5A). These...

Single chip deep ultraviolet light-emitting diodes with junction area up to 1 mm2 were fabricated for high power applications. Lateral geometry devices designed low operating voltage, uniform current spreading and emission resulting in substantial improvement of performance. The maximum CW optical 30 6 mW was achieved emitting at 273 247 nm, respectively.

Self-powered ultraviolet photodetectors generally operate by utilizing the built-in electric field within heterojunctions or Schottky junctions. However, effectiveness of self-powered detection is severely limited weak field. Hence, advances in modulating are crucial for performance breakthroughs. Here, we suggest a method to enhance taking advantage dual-coupling effect between heterojunction and self-polarization ferroelectrics. Under zero bias, fabricated AgNWs/TiO 2 /PZT/GaN device...

We report on the development of solid-state deep ultraviolet light sources optimized for germicidal applications. Pulsed power levels in excess 10 mW were achieved AlGaN based 265 nm emitting diodes by improving material quality using Migration-Enhanced Metal Organic Chemical Vapor Deposition. Packaged devices reached continuous-wave 237 µW at 30 mA and a pulse exceeding 1.2 A driving current.

We report a new epitaxy procedure for growing extremely low defect density a-plane GaN films over r-plane sapphire. By combining selective area growth through SiO2 mask opening to produce high height width aspect ratio pillars and lateral from their c-plane facets, we obtained fully coalesced films. The excellent structural, optical electrical characteristics of these (SALE) deposited make them ideal efficiency III-N electronic optoelectronic devices.

The near-band-edge (NBE) photoluminescence (PL) of AlGaN layers with different Al content was analyzed in a wide range excitation intensities and temperatures. PL peculiarities indicated that tails density states are formed alloys due to the fluctuation alloy composition. model involving recombination through one type nonradiative center is proposed. dependence NBE integrated intensity on power for weaker than GaN, which attributed carrier localization compositional fluctuations and, thus,...

We report the detailed structure analysis of our AlN∕AlGaN superlattice (SL) grown by pulsed atomic-layer epitaxy (PALE) for dislocation filtering. Due to nature PALE, AlGaN well material itself in SL was found be composed actually an AlxGa1−xN∕AlyGa1−yN short-period (SPSL), with periodicity 15.5Å (≈6 monolayer), determined consistently from high-resolution x-ray diffraction and transmission electron microscopy measurements. The SPSL layers is believed benefit SL’s coherent growth, which...