Improving the Current Spreading by Locally Modulating the Doping Type in the n-AlGaN Layer for AlGaN-Based Deep Ultraviolet Light-Emitting Diodes

Abstract

In this report, we locally modulate the doping type in the n -AlGaN layer by proposing n-AlGaN/p-AlGaN/n-AlGaN (NPN-AlGaN)-structured current spreading layer for AlGaN-based deep ultraviolet light-emitting diodes (DUV LEDs). After inserting a thin p-AlGaN layer into the n-AlGaN electron supplier layer, a conduction band barrier can be generated in the n -type electron supplier layer, which enables the modulation of the lateral current distribution in the p-type hole supplier layer for DUV LEDs. Additionally, according to our studies, the Mg doping concentration, the thickness, the AlN composition for the p-AlGaN insertion layer and the NPN-AlGaN junction number are found to have a great influence on the current spreading effect. A properly designed NPN-AlGaN current spreading layer can improve the optical output power, external quantum efficiency (EQE), and the wall-plug efficiency (WPE) for DUV LEDs.

A review on the low external quantum efficiency and the remedies for GaN-based micro-LEDs

“…Another effective method to tune the current spreading length can be doable by manipulating the vertical resistivity for LEDs [101]. For LEDs with large chip size, we shall properly increase the vertical resistivity by using a PNP-AlGaN junction [66,[101][102][103]. Our group have ever proposed an easy approach to better confine the current by reducing the vertical resistivity, which is achieved by properly decreasing the quantum barrier thickness [104].…”