Advantages of GaN based light-emitting diodes with a p-InGaN hole reservoir layer

Abstract

A p-type InGaN hole reservoir layer (HRL) was designed and incorporated in GaN based light-emitting diodes (LEDs) to enhance hole injection efficiency and alleviate efficiency droop. The fabricated LEDs with p-type HRL exhibited higher light output power, smaller emission energy shift and broadening as compared to its counterpart. Based on electrical and optical characteristics analysis and numerical simulation, these improvements are mainly attributed to the alleviated band bending in the last couple of quantum well and electron blocking layer, and thus better hole injection efficiency. Meanwhile, the efficiency droop can be effectively mitigated when the p-InGaN HRL was used.

On the mechanisms of InGaN electron cooler in InGaN/GaN light-emitting diodes

“…Table 1, from which we can see the effective valence band barrier heights of the quantum barriers for LED II is smaller than those for LED I. It has been reported that the effective valance band barrier height for the p-EBL can be reduced by employing GaN/InGaN as the last quantum barrier, hence promoting the hole injection into InGaN/GaN MQWs [27,28]. However, as found in this work, the same physical principle can be applied to the case when the n-type In 0.10 Ga 0.90 N layer is inserted between n-GaN layer and InGaN/GaN MQW region.…”

Simultaneous enhancement of electron overflow reduction and hole injection promotion by tailoring the last quantum barrier in InGaN/GaN light-emitting diodes

“…Meanwhile, it has been reported that the hole injection efficiency is improved by tailoring the last quantum barrier (LQB) in InGaN/GaN light-emitting diodes without sacrificing the electrons confinement capability. [15][16][17][18][19][20][21] For examples, inserting a p-InGaN layer before the p-EBL, [15][16][17][18] applying a p-InGaN/GaN superlattice as the LQB, 19 p-type doping LQB, 20 and thinning the LQB 21 have previously been proposed. However, all of these approaches have to deal with the Mg back-diffusion to the last few QWs.…”

Advantages of GaN based light-emitting diodes with p-AlGaN/InGaN superlattice last quantum barrier

“…In recent years, people have proposed some possible physical mechanisms for efficiency droop such as poor hole injection efficiency [4], electron leakage [5], polarization effect [6], junction heating [7], carrier delocalization [8], the quantum confined stark effect (QCSE) [9], and the Auger recombination [10]. Among the numerous factors, the severe electron leakage and the poor hole injection efficiency are perceived as a key factor for this issue which has been identified by Wang et al [11] In order to overcome the problem, scientists have proposed various effective structures from many point of views, such as the usage of AlGaN barriers [12], InGaN-AlGaN-InGaN barriers [13], staggered quantum wells (QWs) [14], graded electron blocking layer (EBL) [15], AlGaN/GaN superlattice EBL of gradual Al mole fraction [16] and hole reservoir layer [17] In this work, the performance is improved mainly by adjusting the last quantum barrier of LEDs. Recently, Kuo and co-workers [18] proposed the structure with p-doped last barrier to improve the optical performance of the GaN LEDs basing on conventional LED structures.…”