Effects of quantum barriers and electron-blocking layer in deep-ultraviolet light-emitting diodes

Abstract

The impact of quantum barriers (QBs) and electron-blocking layers (EBL) on the output performance of deep-ultraviolet (DUV) light-emitting diodes (LEDs) is investigated systematically. Specific LED structures with strain-compensated and p-staircase-interlayer configurations are proposed and explored in detail. Simulation results show that Al compositions of both QBs and EBL are critical to the capability of carrier confinement of the active region. A DUV LED structure with excellent output performance can be obtained provided that the QBs and EBL are properly designed via band engineering. Furthermore, LED structures without EBL are also investigated. If the DUV LED has well-designed deeper quantum wells, an excellent output performance can be maintained, even when the LED structure is without EBL.

Improved Wave Function Overlap and Carrier Confinement of AlGaN‐Based Deep‐Ultraviolet Light‐Emitting Diodes with Graded Composition Multiple Quantum Wells

“…[ 22 ] In the simulation, the interface charge densities induced by spontaneous and piezoelectric polarization were calculated according to the method proposed by Fiorentini et al [ 23 ] At the same time, considering the screening effect of defects and injection current, the interface charge density is assumed to be 40% of the theoretical value. [ 6 ] The Shockley–Read–Hall carrier lifetime and Auger recombination coefficient are set to be 5 ns and 1.5 × 10 30 cm 6 s −1 , respectively. Not all photons generated by radiative recombination can escape to the outside of the device, the p‐Al 0.40 Ga 0.60 N and p‐GaN layers can absorb some of photons emitted from the MQWs region, so the internal absorption coefficient is set to be 1000 m −1 .…”

“…Therefore, there is a trade-off between the carrier confinement and the overlap of the wave functions. [6] In particular, the insufficient carrier confinement in the MQWs will result in large amount of electrons concentrated in the last QW (LQW) close to the p-type electron blocking layer (p-EBL), and the electrons would be easily leaked into the p-type region to decrease the emission efficiency, especially at high current density injection. [7][8][9][10] To suppress electron leakage, many studies have focused on the p-EBL, [11][12][13][14] however, the p-EBL might also introduce a higher barrier in the valence band, hindering the injection efficiency of the holes.…”

Band engineering of III-nitride-based deep-ultraviolet light-emitting diodes: a review

“…Additionally, the energy gap difference between QBs and QWs determines the carrier confinement behavior in the MQWs. Particularly, the QBs play a key role in preventing electrons from jumping outside of the QW and the LQB which connects the active region with the p-region of the device is the most critical [97]. Hence, how to leverage the quantum confinement and mitigate the QCSE becomes one of the key strategies for achieving high-efficiency DUV LEDs which will be addressed below.…”

Band-Engineered Structural Design of High-Performance Deep-Ultraviolet Light-Emitting Diodes

“…One multi-layer staircase hetero-structure was proposed for the p-type region of DUV LEDs. Moreover, the materials of n-AlGaN layer, quantum barrier (QB), and EBL were also investigated to probe into the capability of carrier confinement of DUV LEDs in our previous research [15,16]. The simulation results show that these factors are all important to the output performance, while the cross-relation among these factors is complicated which needs further thorough exploration.…”