High optical power and low‐efficiency droop blue light‐emitting diodes using compositionally step‐graded InGaN barrier

Abstract

A compositionally step‐graded (CSG) InGaN barrier is designed for the active region of c ‐plane blue light‐emitting diodes (LEDs). High external quantum efficiencies of 45, 42, 39 and 36% are achieved at current densities of 100, 200, 300 and 400 A/cm 2 , respectively. Compared with GaN barrier devices, LEDs with CSG InGaN barriers showed higher power, lower operating voltage and smaller wavelength blueshift, compared with GaN barrier LEDs. Owing to the low‐voltage performance, higher wall‐plug efficiency can be achieved for blue LEDs with CSG InGaN barriers.