Performance enhancement in AlGaN deep ultraviolet light-emitting diodes with step doping n-AlGaN contact layer

Optimizing the strain level within n-AlGaN contact layer is crucial for achieving high-efficiency deep ultraviolet light-emitting diodes (DUV-LEDs). In this study, a step doping strategy in n-AlGaN containing a lightly-doped bottom layer and a heavily-doped upper layer was proposed. The introduction of the lightly doped bottom layer mitigates issues such as strain accumulation and defect generation associated with heavily-doped n-AlGaN which traditionally impairs epitaxial quality and electrical performance of DUV-LEDs, even though similar dislocation density was identified between two LED samples. Thanks to the more uniform distribution of electron concentration and radiative recombination rate in the quantum well region, DUV-LEDs with step-doped layer exhibits 40% higher light output power compared with traditional structure. This work underscores the potential of doping engineering in advancing the performance of DUV-LEDs.