Chapter 8 Group 111-V Nitride-Based Ultraviolet Blue-Green-Yellow Light-Emitting Diodes and Laser Diodes

Abstract

Publisher Summary Highly efficient InGaN/AlGaN DH blue LEDs with an external quantum efficiency of 5.4% were fabricated by codoping Zn and Si into the InGaN active layer. The output power was as high as 3 mW at a forward current of 20 mA. High-brightness blue LEDs with a luminous intensity over 1 cd will pave the way toward realization of full-color LED displays, especially for outdoor use. In Japan, total power consumption by traffic lights reaches the gigawatt range. The InGaN/AlGaN blue-green LED traffic lights, with an electrical power consumption 12% that of present incandescent bulb traffic lights, hold promise for vast energy savings. The high-performance blue LEDs are also double heterostructures consisting of GaInN active layer sandwiched between high bandgap AlGaN layers. This structure gives high-performance blue LEDs, as discussed in Chapter 8. In addition, high-quality GaN films were obtained using GaN buffer layers instead of AIN buffer layers on a sapphire substrate (Nakamura, 1991). This involved development of a novel two-flow MOCVD reactor for the GaN growth that has two different gas flows. One is the main flow, which carries the reactant gas parallel to the substrate at high velocity.