Enhancing Carrier Injection Using Graded Superlattice Electron Blocking Layer for UVB Light-Emitting Diodes

Janjua, Bilal; Ng, Tien Khee; Alyamani, Ahmed Y.; El‐Desouki, Munir M.; Ooi, Boon S.

doi:10.1109/jphot.2014.2374596

Cited by 8 publications

(3 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…At high injection current levels, it is one of the main causes of efficiency rollover or droop in nitride-based devices. 46 However, the Auger recombination is abnormally lower compared to the radiative recombination rate in the n-polar TJ LED at an emission wavelength of 284 nm. These results suggested that the TJ-LED has a low Trap-Related Dislocation Density (TDD) because, in the TJ-LED, the Auger recombination is minimal in contrast to the radiative recombination rate.…”

Section: Resultsmentioning

confidence: 99%

Advantages of AlGaN Tunnel Junction in N-Polar 284 nm Ultraviolet-B Light Emitting Diode

Rahman,

Ayub,

Sharif

et al. 2024

ECS J. Solid State Sci. Technol.

View full text Add to dashboard Cite

Here an approach is presented to electrically operate the quantum tunnelling probability by exploiting the transported carriers at the interface of p-AlGaN/n-AlGaN/n++-AlGaN tunnel junction (TJ) with moderate Si and Mg-doping levels and optimized thickness with the help of simulation study. The simulation results show that the Augur recombination rate is successfully suppressed and quite a high radiative recombination rate is achieved in the 284 nm N-polar AlGaN-based TJ UV-B LEDs, which is attributed to the improved hole injection toward the MQWs when compared to C-LED (conventional-LED). It is found that C-LED has a maximum IQE (internal quantum efficiency) of 40% under 200 A/cm2 injection current with an efficiency drop of 15%, while the TJ-LED has a maximum IQE of 93% with an efficiency droop of 0%. In addition, TJ-based AlGaN LED emitted power has been improved by 6 times compared to the C-LED structure. This is attributed to the lower Augur recombination rate in the MQWs of N-AlGaN-based TJ UV-B LED. The operating voltages were reduced from 5.2 V to 4.1 V under 200 mA operation, which is attributed to the thickness and doping optimization in TJ and better selection of relatively lower Al-content in the contact layer

show abstract

Section: Resultsmentioning

confidence: 99%

Advantages of AlGaN Tunnel Junction in N-Polar 284 nm Ultraviolet-B Light Emitting Diode

Rahman,

Ayub,

Sharif

et al. 2024

ECS J. Solid State Sci. Technol.

View full text Add to dashboard Cite

show abstract

“…This is because that resonant tunneling of hole, which is a quantum mechanical process, through quantized resonant states generated in the superlattice system. 27,28 Besides, the additional advantage of the SPS structure can enhance the ionization efficiency of the dopants due to the polarization-induced reduction in the acceptor ionization energy. In other words, the hole density is mainly determined by the polarization-induced interface charges at the interface of GaN/InGaN SPS structure.…”

Section: Resultsmentioning

confidence: 99%

Performance Enhancement of Blue InGaN Light-Emitting Diodes with P-GaN/InGaN SPS Last Barrier and P-AlGaN/GaN SPS EBL

Wang

Chiou

Lin

et al. 2016

ECS J. Solid State Sci. Technol.

View full text Add to dashboard Cite

The numerical simulations of blue InGaN/GaN light-emitting diodes (LEDs) with the combined structures of p-GaN/InGaN shortperiod superlattice (SPS) last barrier (LB) and p-AlGaN/GaN SPS electron blocking layer (EBL) are investigated by the Advance Physical Model of Semiconductor Devices (APSYS) program. The simulation results show that the newly designed LEDs get better performances over the original structure of InGaN/GaN LEDs. This is attributed to the enhancement of the hole injection efficiency and the improvement of the polarization field effect between the InGaN well and the GaN barrier layer in the multiple quantum wells (MQWs). Therefore, the simulation results exhibit a significant increment in radiative recombination rate and about 2.6 times enhancement in the internal quantum efficiency (IQE) at an injection current of 150 mA. More important of all, it also shows that the newly designed structure can obviously reduce the ratio of efficiency droop of the LEDs from 62 to 14.5%.The high-brightness InGaN/GaN LEDs are considered to be the most candidates in the applications on liquid crystal display back lighting, automobile headlamps, and solid-state lighting. However, the efficiency droop is still a serious issue for high-power LEDs applications. It is known that this phenomenon with the significantly reduction of the efficiency of LEDs at high current density has been called the "efficiency droop". Regarding the mechanisms of efficiency droop, several possible causes for the efficiency droop include poor carrier confinement, 1 Auger recombination, 2-4 electron leakage, 5-7 and poor hole injection. 8-10 However, the origin of the efficiency droop mechanism for nitride-based LEDs is still a controversial and uncertain issue until now. Among them, the insufficient hole injection efficiency and the electron overflow effect are very important key issues due to the relatively low mobility of the hole compared with the electron and insufficient potential barrier height for the electron in the conduction band for GaN-based materials. The conventional bulk p-AlGaN EBL between the LB and p-GaN layer acted as a potential barrier for the electron in the conduction band can effectively suppress the electron overflow from the MQWs to the p-GaN layer. However, the conventional bulk p-AlGaN EBL also created a potential barrier for the hole in the valence band, which obstructed the hole injected into the active region. 11 Consequently, some studies have had some specific designs of the LB structure to improve the carrier injection and reduce the efficiency droop in the GaN-based LEDs, such as a p-doped LB and a p-doped SPS LB. 12,13 In addition, several different energy band engineering designs on EBL also have been suggested like as: a graded p-AlGaN EBL, a p-AlGaN/GaN SPS EBL, and a triangle shape pAlGaN/GaN/AlGaN EBL. 14-16 The purposes of these designs are the improvement of the hole concentration and the enhancement of the radiative recombination rate in the MQWs.On the other hand, GaN-based materials generally exis...

show abstract

“…In similar scenarios, the term polarization-induced 'doping' has been widely used in the literature, which should be physically referred to as an increase in 'carrier' concentrations (not the dopant concentration). Further, a graded-AlGaN layer [76,[96][97][98][99] can assist the hole transport from the p-type cladding layer towards the active regions [100][101][102]. As shown in figures 5(a)-(c), hole transport can be facilitated by replacing the bulk AlGaN electron blocking layer (EBL) with a graded-AlGaN EBL or alternating AlN/AlGaN superlattice (SL) layers, thereby reducing the valence band offset or increasing the hole tunneling probability [96,97,103,104].…”

Section: Te-tm Polarization Issuesmentioning

confidence: 99%

Group-III-nitride and halide-perovskite semiconductor gain media for amplified spontaneous emission and lasing applications

Ng¹,

Holguín‐Lerma²,

Kang³

et al. 2021

J. Phys. D: Appl. Phys.

Self Cite

View full text Add to dashboard Cite

Group-III-nitride optical devices are conventionally important for displays and solid-state lighting, and recently have garnered much interest in the field of visible-light communication. While visible-light laser technology has become mature, developing a range of compact, small footprint, high optical power components for the green-yellow gap wavelengths still requires material development and device design breakthroughs, as well as hybrid integration of materials to overcome the limitations of conventional approaches. The present review focuses on the development of laser and amplified spontaneous emission (ASE) devices in the visible wavelength regime using primarily group-III-nitride and halide-perovskite semiconductors, which are at disparate stages of maturity. While the former is well established in the violet-blue-green operating wavelength regime, the latter, which is capable of solution-based processing and wavelength-tunability in the green-yellow-red regime, promises easy heterogeneous integration to form a new class of hybrid semiconductor light emitters. Prospects for the use of perovskite in ASE and lasing applications are discussed in the context of facile fabrication techniques and promising wavelength-tunable light-emitting device applications, as well as the potential integration with group-III-nitride contact and distributed Bragg reflector layers, which is promising as a future research direction. The absence of lattice-matching limitations, and the presence of direct bandgaps and excellent carrier transport in halide-perovskite semiconductors, are both encouraging and thought-provoking for device researchers who seek to explore new possibilities either experimentally or theoretically. These

show abstract

Enhancing Carrier Injection Using Graded Superlattice Electron Blocking Layer for UVB Light-Emitting Diodes

Cited by 8 publications

References 45 publications

Advantages of AlGaN Tunnel Junction in N-Polar 284 nm Ultraviolet-B Light Emitting Diode

Advantages of AlGaN Tunnel Junction in N-Polar 284 nm Ultraviolet-B Light Emitting Diode

Performance Enhancement of Blue InGaN Light-Emitting Diodes with P-GaN/InGaN SPS Last Barrier and P-AlGaN/GaN SPS EBL

Group-III-nitride and halide-perovskite semiconductor gain media for amplified spontaneous emission and lasing applications

Contact Info

Product

Resources

About