Performance improvement of blue InGaN light-emitting diodes with a specially designed n-AlGaN hole blocking layer

Blue InGaN light-emitting diodes (LEDs) with a conventional electron blocking layer (EBL), a common n-AlGaN hole blocking layer (HBL), and an n-AlGaN HBL with gradual Al composition are investigated numerically, which involves analyses of the carrier concentration in the active region, energy band diagram, electrostatic field, and internal quantum efficiency (IQE). The results indicate that LEDs with an n-AlGaN HBL with gradual Al composition exhibit better hole injection efficiency, lower electron leakage, and a smaller electrostatic field in the active region than LEDs with a conventional p-AlGaN EBL or a common n-AlGaN HBL. Meanwhile, the efficiency droop is alleviated when an n-AlGaN HBL with gradual Al composition is used.     

Performance improvement of GaN-based light-emitting diode with a p-InAIGaN hole injection layer

The characteristics of a blue light-emitting diode （LED） with a p-InA1GaN hole injection layer （HIL） is analyzed numerically. The simulation results indicate that the newly designed structure presents superior optical and electrical performance such as an increase in light output power, a reduction in current leakage and alleviation of efficiency droop. These improvements can be attributed to the p-InA1GaN serving as hole injection layers, which can alleviate the band bending induced by the polarization field, thereby improving both the hole injection efficiency and the electron blocking efficiency.     

The advantage of blue InGaN multiple quantum wells light-emitting diodes with p-AlInN electron blocking layer

InGaN based light-emitting diodes (LEDs) with different electron blocking layers have been numerically investigated using the APSYS simulation software. It is found that the structure with a p-AlInN electron blocking layer showes improved light output power, lower current leakage, and smaller efficiency droop. Based on numerical simulation and analysis, these improvements of the electrical and optical characteristics are mainly attributed to the efficient electron blocking in the InGaN/GaN multiple quantum wells (MQWs).     

Improved performance of InGaN light-emitting diodes with a novel sawtooth-shaped electron blocking layer

A sawtooth-shaped electron blocking layer is proposed to improve the performance of light-emitting diodes （LEDs）. The energy band diagram, the electrostatic field in the quantum well, the carrier concentration, the electron leakage, and the internal quantum efficiency are systematically studied. The simulation results show that the LED with a sawtooth-shaped electron blocking layer possesses higher output power and a smaller efficiency droop than the LED with a conventional A1GaN electron blocking layer, which is because the electron confinement is enhanced and the hole injection efficiency is improved by the appropriately modified electron blocking layer energy band.     

Droop improvement in blue InGaN light-emitting diodes with GaN/InGaN superlattice barriers

GaN/InGaN superlattice barriers are used in InGaN-based light-emitting diodes （LEDs）. The electrostatic field in the quantum wells, electron hole wavefunction overlap, carrier concentration, spontaneous emission spectrum, light-current performance curve, and internal quantum efficiency are numerically investigated using the APSYS simulation software. It is found that the structure with GaN/InGaN superlattice barriers shows improved light output power, and lower current leakage and efficiency droop. According to our numerical simulation and analysis, these improvements in the electrical and optical characteristics are mainly attributed to the alleviation of the electrostatic field in the active region.     

Performance improvement of GaN-based light-emitting diode with a p-InAlGaN hole injection layer

The characteristics of a blue light-emitting diode(LED)with a p-InAlGaN hole injection layer(HIL)is analyzed numerically.The simulation results indicate that the newly designed structure presents superior optical and electrical performance such as an increase in light output power,a reduction in current leakage and alleviation of efficiency droop.These improvements can be attributed to the p-InAlGaN serving as hole injection layers,which can alleviate the band bending induced by the polarization field,thereby improving both the hole injection efficiency and the electron blocking efficiency.     

Performance improvement of InGaN blue light-emitting diodes with several kinds of electron-blocking layers

The performance of InGaN blue light-emitting diodes(LEDs) with different kinds of electron-blocking layers is investigated numerically.We compare the simulated emission spectra,electron and hole concentrations,energy band diagrams,electrostatic fields,and internal quantum efficiencies of the LEDs.The LED using AlGaN with gradually increasing Al content from 0% to 20% as the electron-blocking layer(EBL) has a strong spectrum intensity,mitigates efficiency droop,and possesses higher output power compared with the LEDs with the other three types of EBLs.These advantages could be because of the lower electron leakage current and more effective hole injection.The optical performance of the specifically designed LED is also improved in the case of large injection current.     

Enhanced performances of InGaN/GaN-based blue light-emitting diode with InGaN/AlInGaN superlattice electron blocking layer

InGaN/AlInGaN superlattice(SL) is designed as the electron blocking layer(EBL) of an InGaN/GaN-based lightemitting diode(LED). The energy band structure, polarization field at the last-GaN-barrier/EBL interface, carrier concentration, radiative recombination rate, electron leakage, internal quantum efficiency(IQE), current–voltage(I–V) performance curve, light output–current(L–I) characteristic, and spontaneous emission spectrum are systematically numerically investigated using APSYS simulation software. It is found that the fabricated LED with InGaN/AlInGaN SL EBL exhibits higher light output power, low forward voltage, and low current leakage compared with those of its counterparts.Meanwhile, the efficiency droop can be effectively mitigated. These improvements are mainly attributed to the higher hole injection efficiency and better electron confinement when InGaN/AlInGaN SL EBL is used.     

Enhanced performances of InGaN/GaN-based blue light-emitting diode with InGaN/AIInGaN superlattice electron blocking layer

InGaN/AIlnGaN superlattice （SL） is designed as the electron blocking layer （EBL） of an InGaN/GaN-based light- emitting diode （LED）. The energy band structure, polarization field at the last-GaN-barrier/EBL interface, carrier concen- tration, radiative recombination rate, electron leakage, internal quantum efficiency （IQE）, current-voltage （l-V） perfor- mance curve, light output-current （L-l） characteristic, and spontaneous emission spectrum are systematically numerically investigated using APSYS simulation software. It is found that the fabricated LED with InGaN/AIInGaN SL EBL exhibits higher light output power, low forward voltage, and low current leakage compared with those of its counterparts. Meanwhile, the efficiency droop can be effectively mitigated. These improvements are mainly attributed to the higher hole injection efficiency and better electron confinement when InGaN/AIlnGaN SL EBL is used.     

Performance enhancement of an InGaN light-emitting diode with an AIGaN/InGaN superlattice electron-blocking layer

The efficiency enhancement of an InGaN light-emitting diode （LED） with an A1GaN/InGaN superlattice （SL） electron-blocking layer （EBL） is studied numerically, which involves the light-current performance curve, internal quan- tum efficiency electrostatic field band wavefunction, energy band diagram carrier concentration, electron current density, and radiative recombination rate. The simulation results indicate that the LED with an A1GaN/InGaN SL EBL has better optical performance than the LED with a conventional rectangular A1GaN EBL or a normal A1GaN/GaN SL EBL because of the appropriately modified energy band diagram, which is favorable ibr the injection of holes and confinement of elec- trons. Additionally, the efficiency droop of the LED with an AIGaN/InGaN SL EBL is markedly improved by reducing the polarization field in the active region.     

Efficiency enhancement of InGaN based blue light emitting diodes with InGaN/GaN multilayer barriers

The advantages of InGaN based light-emitting diodes with InGaN/GaN multilayer barriers are studied.It is found that the structure with InGaN/GaN multilayer barriers shows improved light output power,lower current leakage,and less efficiency droop over its conventional InGaN/GaN counterparts.Based on the numerical simulation and analysis,these improvements on the electrical and the optical characteristics are mainly attributed to the alleviation of the electrostatic field in the quantum wells(QWs) when the InGaN/GaN multilayer barriers are used.     

Simulation study of blue InGaN multiple quantum well light-emitting diodes with different hole injection layers

InGaN-based light-emitting diodes with p-GaN and p-AlGaN hole injection layers are numerically studied using the APSYS simulation software.The simulation results indicate that light-emitting diodes with p-AlGaN hole injection layers show superior optical and electrical performance,such as an increase in light output power,a reduction in current leakage and alleviation of efficiency droop.These improvements can be attributed to the p-AlGaN serving as hole injection layers,which can alleviate the band bending induced by the polarization field,thereby improving both the hole injection efficiency and the electron blocking efficiency.     

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

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.     

In组分渐变提高InGaN/GaN多量子阱发光二极管发光性能

利用金属有机物化学气相沉积系统在蓝宝石衬底上通过有源层的变温生长,得到In组分渐变的量子阱结构,从而获得具有三角形能带结构的InGaN/GaN多量子阱发光二极管(LED)(简称三角形量子阱结构LED).变温光致发光谱结果表明,相对于传统具有方形能带结构的量子阱LED(简称方形量子阱结构LED),三角形量子阱结构有效提高了量子阱中电子和空穴波函数的空间交叠,从而增加了LED的内量子效率;电致发光谱结果表明,三角形量子阱结构LED器件与传统结构LED器件相比,明显改善了发光峰值波长随着电流的蓝移现象.通过以上     

Improving the color purity and efficiency of blue organic light-emitting diodes (BOLED) by adding hole-blocking layer

This work demonstrates the fabrication of a bright blue organic light-emitting diode (BOLED) with good color purity using 4,4′-bis(2,2-diphenylvinyl)-1,1′-biphenyl (DPVBi) and bathocuproine (BCP) as the emitting layer (EML) and the hole-blocking layer (HBL), respectively. Devices were prepared by vacuum deposition on indium tin oxide (ITO)-glass substrates. The thickness of DPVBi used in the OLED has an important effect on color and efficiency. The blue luminescence is maximal at 7670 cd/m² when 13 V is applied and the BCP thickness is 2 nm. The CIE coordinate at a luminance of 7670 cd/m² is (0.165, 0.173). Furthermore, the current efficiency is maximum at 4.25 cd/A when 9 V is applied.     

Performance enhancement of an InGaN light-emitting diode with an AlGaN/InGaN superlattice electron-blocking layer

The efficiency enhancement of an InGaN light-emitting diode(LED) with an AlGaN/InGaN superlattice(SL)electron-blocking layer(EBL) is studied numerically,which involves the light-current performance curve,internal quantum efficiency electrostatic field band wavefunction,energy band diagram carrier concentration,electron current density,and radiative recombination rate.The simulation results indicate that the LED with an AlGaN/InGaN SL EBL has better optical performance than the LED with a conventional rectangular AlGaN EBL or a normal AlGaN/GaN SL EBL because of the appropriately modified energy band diagram,which is favorable for the injection of holes and confinement of electrons.Additionally,the efficiency droop of the LED with an AlGaN/InGaN SL EBL is markedly improved by reducing the polarization field in the active region.     

Performance improvement of blue light-emitting diodes with an AlInN/GaN superlattice electron-blocking layer

The characteristics of a blue light-emitting diode (LED) with an AlInN/GaN superlattice (SL) electron-blocking layer (EBL) are analyzed numerically. The carrier concentrations in the quantum wells, energy band diagrams, electrostatic fields, and internal quantum efficiency are investigated. The results suggest that the LED with an AlInN/GaN SL EBL has better hole injection efficiency, lower electron leakage, and smaller electrostatic fields in the active region than the LED with a conventional rectangular AlGaN EBL or a AlGaN/ GaN SL EBL. The results also indicate that the efficiency droop is markedly improved when an AlInN/GaN SL EBL is used.     

利用山形空穴存储层结构对深紫外激光二极管的性能优化

为了有效提高深紫外激光二极管的空穴注入效率和减少电子泄露,优化其性能,设计出了在基础矩形空穴存储层结构上改进后的山形空穴存储层和倒山形空穴存储层。使用Crosslight软件模拟仿真倒山形和山形空穴存储层结构的电子浓度、电子电流密度、能带图以及P-I特性曲线。结果显示山形空穴存储层激光器的光学和电学性能优于矩形和倒山形激光器,因此山形空穴存储层激光器能有效地增加有源区空穴注入和减少电子泄露,提高有源区载流子浓度和辐射复合速率,实现了激光器优越的光电性能。