Existing barriers to efficient deep ultraviolet (UV) light-emitting diodes (LEDs) may be reduced or overcome by moving away from conventional planar growth and toward three-dimensional nanostructuring. Nanorods have the potential for enhanced doping, reduced dislocation densities, improved light extraction efficiency, and quantum wells free from th...
Existing barriers to efficient deep ultraviolet (UV) light-emitting diodes (LEDs) may be reduced or overcome by moving away from conventional planar growth and toward three-dimensional nanostructuring. Nanorods have the potential for enhanced doping, reduced dislocation densities, improved light extraction efficiency, and quantum wells free from th...
We investigated the formation of ohmic contacts as a result of intermetallic phase formation between V, Al, Ni, and Au in V/Al/Ni/Au metal stacks on n-Al0.65Ga0.35N:Si. In particular, the influence of Au metal thickness and annealing temperature was analysed. The lowest annealing temperature of 750 °C for an ohmic contact with a smooth surface and ...
Published in Semiconductor Science and Technology
We investigated the formation of ohmic contacts as a result of intermetallic phase formation between V, Al, Ni, and Au in V/Al/Ni/Au metal stacks on n-Al0.65Ga0.35N:Si. In particular, the influence of Au metal thickness and annealing temperature was analysed. The lowest annealing temperature of 750 °C for an ohmic contact with a smooth surface and ...
Published in Applied Physics Express
AlGaN-based deep ultraviolet (DUV) micro-light-emitting diodes (μLEDs) with emission wavelengths between 277 and 304 nm with mesa dimensions down to 20 μm were fabricated. Their size-dependent electrical and optical characteristics were analyzed. At 20 A cm−2, the external quantum efficiency (EQE) increased from 2.0% to 2.3% mainly due to the impro...
Published in Semiconductor Science and Technology
Increase of light extraction efficiency (LEE) and total output power of UV light emitting diodes (LEDs) emitting at 265 and 310 nm, respectively, after encapsulation with a UV-transparent silicone are studied. Raytracing simulations suggest that a properly placed hemispherical encapsulation with a refractive index in the range from 1.4 to 1.8 enhan...
Published in Applied Physics Express
We demonstrated the structural optimization of AlGaN tunnel junction (TJ) deep-ultraviolet light-emitting diodes by changing the thickness and impurity concentrations of p+-type and n+-type AlGaN constituting the TJ. By decreasing the total thickness of the TJ to 23 nm, the operating voltage reached a minimum of 8.8 V at 63 A cm−2. Further decrease...
Published in Applied Physics Express
We analyzed the p–n junction of an aluminum gallium nitride (AlGaN) homojunction tunnel junction (TJ) deep-ultraviolet light-emitting diode by phase-shifting electron holography. We clearly obtained a phase image reflecting the band alinement of the p–n homojunction and derived a depletion layer width of approximately 10 nm. In addition, the observ...
As it is high in value, extra virgin olive oil (EVOO) is frequently blended with inferior vegetable oils. This study presents an optical method for determining the adulteration level of EVOO with soybean oil as well as peanut oil using LED-induced fluorescence spectroscopy. Eight LEDs with central wavelengths from ultra-violet (UV) to blue are test...
In this work, the use of commercial UV LED lamps (395 nm, IP 68 certification, and 0.08 W) was evaluated for the reduction of Ibuprofen (IBP) concentration in an aqueous solution. The measurements of pH and initial concentration of the PPI in the solution were the experimental variables used to determine its effect on the percentage of reduction of...
