Optical Performance of N-Face AlGaN Ultraviolet Light Emitting Diodes

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 ptype 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.

Section: Introductionmentioning

confidence: 99%

Double superlattice structure for improving the performance of ultraviolet light-emitting diodes

Wang

et al. 2019

“…AlGaN ternary compound has attracted much interest due to its wide application in light-emitting devices, [1,2] solarblind ultraviolet (UV) detectors, [3,4] and high-power and hightemperature electronic devices. [5,6] With the band gap varying from 3.4 eV to 6.2 eV, it is an ideal semiconductor for UV applications, especially light-emitting devices.…”

Section: Introductionmentioning

confidence: 99%

Enhancing redshift phenomenon in time-resolved photoluminescence spectra of AlGaN epilayer

Jin

Wang

et al. 2017

AlGaN epitaxial layer has been studied by means of temperature-dependent time-integrated photoluminescence (PL) and time-resolved photoluminescence (TRPL). An enhancing redshift phenomenon in TRPL spectra with increasing temperature was observed, and the localized excitons behaved like quasi two-dimensional excitons between 6 K and 90 K. We demonstrated that these behaviors are caused by a change in the carrier dynamics with increasing temperature due to the competition of carriers' localization and delocalization in the AlGaN alloy.

“…The reasons can be attributed to their extensive roles in science research and daily life, such as chemical sensors, medical applications, water sterilization, full-color displays, etc. [14][15][16] Despite the attractive prospect, there are also several challenges to the AlGaN-based UV-LED, such as poor hole injection efficiency and electron leakage from multi-quantum wells (MQWs) into the p-type layers, which leads to low carrier concentrations in active layers and weak radioactive recombination. [17,18] In recent years, various approaches have been put forward to cope with those challenges.…”

Section: Introductionmentioning

confidence: 99%

Performance improvement of AlGaN-based deep ultraviolet light-emitting diodes with double electron blocking layers

Zhang¹,

Sun²,

Li³

et al. 2016

The AlGaN-based deep ultraviolet light-emitting diodes (LED) with double electron blocking layers (d-EBLs) on both sides of the active region are investigated theoretically. They possess many excellent performances compared with the conventional structure with only a single electron blocking layer, such as a higher recombination rate, improved light output power and internal quantum efficiency (IQE). The reasons can be concluded as follows. On the one hand, the weakened electrostatic field within the quantum wells (QWs) enhances the electron–hole spatial overlap in QWs, and therefore increases the probability of radioactive recombination. On the other hand, the added n-AlGaN layer can not only prevent holes from overflowing into the n-side region but also act as another electron source, providing more electrons.