Improving the hole injection efficiency in AlGaN DUV LEDs by minimizing the band offset at the p-EBL/hole supplier interface

Abstract

In AlGaN-based deep ultraviolet light-emitting diodes (DUV LEDs), the large valence band offset between the Al-rich electron blocking layer (EBL) and p-AlGaN hole supplier weakens the chance of holes being injected into the active region. Only holes with kinetic energy larger than the barrier height at the EBL/p-AlGaN interface are allowed to climb over the EBL before entering the active region, limiting the hole injection efficiency and thus reducing the external quantum efficiency (EQE). In this work, we incorporate a thin AlGaN insertion layer between EBL and the p-AlGaN hole supplier to enhance the hole injection efficiency of DUV LEDs via regulating the energy band at the p-EBL/p-AlGaN interface. By systematically investigating and analyzing the effects of aluminum components in the insertion layers on the hole injection and the electron confinement, we found that the insertion layer with an Al composition of 45% can effectively enhance the EQE of DUV LEDs by 40.5% and suppress efficiency droop by 65.5%. The design strategy provides an effective approach to boost the hole injection efficiency for AlGaN-based DUV LEDs.