To improve the light extraction efficiency of InGaN-light emitting diode (LED), inverted hexagonal cone shaped air voids with {10–11} GaN crystal planes were formed between a patterned sapphire substrate and GaN epitaxial layer using a H3PO4-based hot chemical etching method. The air-voids embedded LED showed 12% and 210% higher optical power than a patterned substrate LED and a flat substrate LED, respectively. A ray tracing simulation revealed that the light extraction through the top face of the air-voids embedded LED was dramatically increased due to a strong light reflection and redirection by the air voids.
The effect of silicon doping in the selected barrier on the electroluminescence of InGaN∕GaN multiquantum well light emitting diode (LED) was studied using dual wavelength LEDs. The result verified that the hole carrier transport is easily blocked by the silicon doped barrier, and the dominant electron and hole recombination occurs at the wells between p-GaN and the silicon doped barrier. The electroluminescence spectrum and the wavelength blueshift of the silicon doped LEDs were compared with undoped LEDs. The numerical simulation was done to clearly explain the hole blocking effect by the silicon doped barrier.
Articles you may be interested inIn situ X-ray investigation of changing barrier growth temperatures on InGaN single quantum wells in metalorganic vapor phase epitaxy J. Appl. Phys. 115, 094906 (2014); 10.1063/1.4867640 Metal-organic chemical vapor deposition growth of InGaN/GaN high power green light emitting diode: Effects of InGaN well protection and electron reservoir layer J. Appl. Phys. 102, 053519 (2007); 10.1063/1.2776218
High quality InN/GaN heterostructures grown by migration enhanced metalorganic chemical vapor depositionInGaN layers have been grown on ͑0001͒ ZnO substrates by metalorganic chemical vapor deposition utilizing a low temperature grown thin GaN buffer. Good quality InGaN films with a wide range of In composition were confirmed by high-resolution x-ray diffraction. Even at high indium concentrations no In droplets and phase separation appeared, possibly due to coherent growth of InGaN on ZnO. Photoluminescence showed broad InGaN-related emissions with peak energy lower than the calculated InGaN band gap, possibly due to Zn/O impurities diffused into InGaN from the ZnO substrate. An activation energy of 59 meV for the InGaN epilayer is determined.
The electrostatic discharge (ESD) properties of the InGaN-light emitting diode (LED) were investigated in terms of the internal capacitance of the InGaN-LED. The LEDs with higher internal capacitance were found to be more resistant to external ESD impulses. The internal capacitance of the InGaN-LED was controlled by the silicon doping level of the n-GaN layer bordering the active layer. The human body model ESD yield at −500 V was increased from 27% to 94% by increasing the internal capacitance. Moreover, the high ESD pass yield was maintained up to −7000 V.
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