III-V nitride-based light-emitting diodes

Abstract

Materials characteristics of undoped GaN, p-type GaN and InGaN are described using Hall, X-ray diffraction and photoluminescence measurements. Recent breakthroughs in growth methods of III-V nitrides have opened the way to obtaining high-quality InGaN and AlGaN epitaxial films. High-power blue, green and yellow light-emitting diodes (LEDs) with quantum-well structures based on III-V nitrides were grown by metal-organic chemical vapor deposition on sapphire substrates. The typical blue LEDs had a peak wavelength of 450 nm and full width at half-maximum (FWHM) of 20 nm. The output power, the external quantum efficiency and the luminous intensity of blue LEDs at a forward current of 20 mA were 4 mW, 7.3% and 2 cd, respectively. Typical yellow LEDs had a peak wavelength of 590 nm and FWHM of 90 nm. The output power of yellow LEDs was 0.5 mW at 20 mA. When the emission wavelength of III-V nitride LEDs with quantum-well structures increased from the region of blue to yellow, the output power decreased dramatically.