Fabrication of high-brightness blue InGaN/GaN MQW LEDs

In this article, we report the successful fabrication of high-brightness blue LEDs with InGaN/GaN multiple quantum well (MQW) structures grown by low pressure metalorganic vapor phase epitaxy (LP-MOVPE) on sapphire substrates. The active region is composed of five pairs of InGaN well and GaN:Si barrier. The epitaxial wafer is processed into mesa diodes by inductively coupled plasma (ICP) etching technique, with SiO2 deposited by plasma-enhanced chemical vapor deposition (PECVD) as the etching mask. The diode chips are then encapsulated into transparent epoxy to form packaged LEDs. The typical emitting spectrum of the blue LEDs shows a peak wavelength at 460 nm and a FWHM of 30 nm. The working voltage and output power of blue LEDs at a forward current of 20 mA are 3.6V and 1.5 mW, respectively. The reverse leakage current at 5V was about 5 muA, and the wavelength uniformity is 0.25 nm.