InGaN-Based Light-Emitting Diodes With an AlGaN Staircase Electron Blocking Layer

Applied Physics Letters

Kyaw

et al. 2013

The effect of n-AlGaN versus p-AlGaN electron-blocking layers (EBLs) on the performance of InGaN/GaN light-emitting diodes is studied in this work. Experimental results suggest that the n-type EBL leads to higher optical output power and external quantum efficiency, compared to the devices with p-AlGaN EBL, which is commonly used today. Numerical simulations on the carrier distribution and energy band diagram reveal that the n-AlGaN EBL is more efficient in preventing electron overflow, while not blocking the hole injection into the active region, hence leading to higher radiative recombination rate within the multiple quantum wells active region. © 2013 AIP Publishing LLC

mentioning

confidence: 99%

Influence of n-type versus p-type AlGaN electron-blocking layer on InGaN/GaN multiple quantum wells light-emitting diodes

Applied Physics Letters

Kyaw

et al. 2013

“…10 Therefore, different p-EBL structures have been reported to increase the hole injection, such as the superlattice p-EBL 11 and staircase p-EBL. 12 Recently, the AlGaN/GaN/AlGaN p-EBL with a very thin GaN insertion layer is proposed where the valence subbands in the thin GaN insertion layer can significantly reduce the p-EBL barrier height for holes. 13 The p-EBL blocking effect can also be suppressed by making holes "hot" 14 and/or increasing the hole concentration in the p-GaN layer through a hole modulator.…”

mentioning

confidence: 99%

A charge inverter for III-nitride light-emitting diodes

Applied Physics Letters

et al. 2016

In this work, we propose a charge inverter that substantially increases the hole injection efficiency for InGaN/GaN light-emitting diodes (LEDs). The charge inverter consists of a metal/electrode, an insulator, and a semiconductor, making an Electrode-Insulator-Semiconductor (EIS) structure, which is formed by depositing an extremely thin SiO2 insulator layer on the p+-GaN surface of a LED structure before growing the p-electrode. When the LED is forward-biased, a weak inversion layer can be obtained at the interface between the p+-GaN and SiO2 insulator. The weak inversion region can shorten the carrier tunnel distance. Meanwhile, the smaller dielectric constant of the thin SiO2 layer increases the local electric field within the tunnel region, and this is effective in promoting the hole transport from the p-electrode into the p+-GaN layer. Due to the improved hole injection, the external quantum efficiency is increased by 20% at 20 mA for the 350 × 350 μm2 LED chip. Thus, the proposed EIS holds great promise for high efficiency LEDs.

“…6 In practice, the graded Al composition EBL and the superlattice EBL are not easy to be realized since they need very precise control of the composition and the thickness of the EBL layer. 7 For quaternary AlInGaNand AlInN-type EBLs, due to the large difference of AlN and InN in bonding strength and thermal property, the growth has to be conducted at a low temperature with N 2 as carrier gas. Therefore, the growth conditions are difficult to control and the material quality is often compromised.…”

mentioning

confidence: 99%

“…These approaches include p-AlGaN EBLwith graded Al composition, AlGaN/GaN superlattice EBL, AlInGaN quaternary EBL, and AlInN EBL . In practice, the graded Al composition EBL and the superlattice EBL are not easy to be realized since they need very precise control of the composition and the thickness of the EBL layer . For quaternary AlInGaN- and AlInN-type EBLs, due to the large difference of AlN and InN in bonding strength and thermal property, the growth has to be conducted at a low temperature with N 2 as carrier gas.…”

mentioning

confidence: 99%

Advantages of the Blue InGaN/GaN Light-Emitting Diodes with an AlGaN/GaN/AlGaN Quantum Well Structured Electron Blocking Layer

Liu

et al. 2014

ACS Photonics

InGaN/GaN light-emitting diodes (LEDs) with p-(AlGaN/GaN/AlGaN) quantum well structured electron blocking layer (QWEBL) are designed and grown by a metal− organic chemical-vapor deposition (MOCVD) system. The proposed QWEBL LED structure, in which a p-GaN QW layer is inserted in the p-AlGaN electron blocking layer, not only leads to an improved hole injection but also reduces the electron leakage, thus enhancing the radiative recombination rates across the active region. Consequently, the light output power was enhanced by 10% for the QWEBL LED at a current density of 35 A/cm 2 . The efficiency droop of the optimized device was reduced to 16%. This is much smaller than that of the conventional p-AlGaN electron blocking layer LED, which is 31%.