Fabrication and Characterization of GaN-based White LED on 4-inch Patterned Sapphire Substrate

A blue light emitting diode(LED) chip has been fabricated on a 4-inch patterned sapphire substrate with an InGaN/GaN multiple quantum well structure. It has also been combined with a yttrium aluminum garnet yellow phosphor(YAG: Ce3+) to be packaged into a white LED device. In this study, its epitaxial growth, chip process and packaging process have been briefly described. Some material property and device performance have been characterized. The surface of the epitaxial wafer has a good morphology. The photoluminescence(PL) spectrum of the blue epitaxial wafer shows a peak wavelength of 442 nm. Basing on the electrical characteristics of the packaged white light chip, the threshold and current-limit voltages are 2.7 V and 3.6 V, respectively. In addition, the electroluminescence(EL) spectra contain two main peaks with one at 440 nm of blue light and the other one at 540 nm of yellow-green light. With the increase of the injection current, the blue peak varies from blue-shift to red-shift, and the yellow-green varies from red-shift to blue-shift and then red-shift. It is believed that the related chip fabrication and characterization technology would play a certain role in the research for promoting on solid-state lighting field. © 2020, Science Press. All right reserved.