Double superlattice structure for improving the performance of ultraviolet light-emitting diodes**Project supported by the National Key R&D Program of China (Grant Nos. 2016YFB0400800, 2016YFB0400801, and 2016YFB0400802), the National Natural Science Foundation of China (Grant No. 61634005), and the Fundamental Research Funds for the Central Universities, China (Grant No. JBZ171101).

Abstract

The novel AlGaN-based ultraviolet light-emitting diodes (UV-LEDs) with double superlattice structure (DSL) are proposed and demonstrated by numerical simulation and experimental verification. The DSL consists of 30-period Mg modulation-doped p-AlGaN/u-GaN superlattice (SL) and 4-period p-AlGaN/p-GaN SL electron blocking layer, which are used to replace the p-type GaN layer and electron blocking layer of conventional UV-LEDs, respectively. Due to the special effects and interfacial stress, the AlGaN/GaN short-period superlattice can reduce the acceptor ionization energy of the p-type regions, thereby increasing the hole concentration. Meanwhile, the multi-barrier electron blocking layers are effective in suppressing electron leakage and improving hole injection. Experimental results show that the enhancements of 22.5% and 37.9% in the output power and external quantum efficiency at 120 mA appear in the device with double superlattice structure.