Performance enhancement of InGaN LEDs with Al-graded GaN/AlGaN multiple electron-blocking layers

Abstract

The characteristics of InGaN-based flip-chip light-emitting diodes (LEDs) with Al-graded-composition GaN/AlGaN multiple electron-blocking layers (MEBLs) are investigated. Results showed that MEBL LED samples with differently graded Al mole fractions possess a higher light output power and a lower efficiency droop than a conventional EBL LED while avoiding the operating voltage penalty. These improvements are mainly attributed to the improvements in electron confinement and hole injection efficiency caused by mitigating the polarization-induced band-bending effect at the interface between the last barrier of multiple quantum wells and the EBL.