Improving hole injection efficiency by manipulating the hole transport mechanism through p-type electron blocking layer engineering

Abstract

The $p$-type AlGaN electron blocking layer (EBL) is widely used in InGaN/GaN light-emitting diodes (LEDs) for electron overflow suppression. However, a typical EBL also reduces the hole injection efficiency, because holes have to climb over the energy barrier generated at the $p\text{-}\mathrm{AlGaN}/p\text{-}\mathrm{GaN}$ interface before entering the quantum wells. In this work, to address this problem, we report the enhancement of hole injection efficiency by manipulating the hole transport mechanism through insertion of a thin GaN layer of 1 nm into the $p$-AlGaN EBL and propose an AlGaN/GaN/AlGaN-type EBL outperforming conventional AlGaN EBLs. Here, the position of the inserted thin GaN layer relative to the $p$-GaN region is found to be the key to enhancing the hole injection efficiency. InGaN/GaN LEDs with the proposed $p$-type AlGaN/GaN/AlGaN EBL have demonstrated substantially higher optical output power and external quantum efficiency.

© 2014 Optical Society of America

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