Improvement of characteristics of an InGaN light-emitting diode by using a staggered AlGaN electron-blocking layer

The optical and physical properties of an InGaN light-emitting diode (LED) with a specific design of a staggered AlGaN electron-blocking layer (EBL) are investigated numerically in detail. The electrostatic field distribution, energy band, carrier concentration, electroluminescence (EL) intensity, internal quantum efficiency (IQE), and the output power are simulated. The results reveal that this specific design has a remarkable improvement in optical performance compared with the design of a conventional LED. The lower electron leakage current, higher hole injection efficiency, and consequently mitigated efficiency droop are achieved. The significant decrease of electrostatic field at the interface between the last barrier and the EBL of the LED could be one of the main reasons for these improvements.     

量子阱垒层掺杂变化对双波长LED调控作用研究

采用APSYS软件研究了InGaN/GaN量子阱垒层掺杂变化对双波长 发光二极管发光光谱的调控问题. 在不同掺杂类型和浓度下对器件电子空穴浓度分布、 载流子复合速率、 能带结构、 发光光谱进行分析, 结果表明, 调节量子阱垒层n型和p型的掺杂浓度可以精确而有效地根据需要调控发光光谱, 解决发光光谱调控难的问题. 这些现象归因于掺杂的量子阱垒层对电子空穴分布的调控作用.     

选择性p型量子阱垒层掺杂在双波长发光二极管光谱调控中的作用

采用软件理论分析的方法对选择性p型掺杂量子阱垒层在InGaN双波长发光 二极管(LED)中的光谱调控作用进行模拟分析.分析结果表明, 选择性p型掺杂对量子阱中电子和空穴浓度分布的均衡性起到一定的调控作用, 在适当选择p型掺杂量子阱垒层层数的条件下,能够改善量子阱中载流子的 辐射复合速率, 降低溢出电子浓度,从而有效提高芯片内量子效率,并减缓内量子效率随驱动 电流增大而快速下降的趋势.随着活性层量子阱增加到特定数量, 选择性p型掺杂的调控效果更加明显, LED芯片的双波长发光峰强度达到基本均衡.     

量子阱数量变化对InGaN/AlGaN LED的影响

采用软件理论分析的方法分析了InGaN/AlGaN量子阱数量变化对发光二极管内量子效率、电子空穴浓度分布、载流子溢出产生的影响。分析结果表明:量子阱的个数不是越多越好,LED的光学性质和量子阱的个数并不成线性关系。量子阱个数太少时,电流溢出现象较明显;而当量子阱个数太多时,极化现象明显,且会造成材料浪费。因此应根据工作电流选择合适的量子阱个数。     

量子阱数量变化对双波长LED作用的研究

采用软件理论分析的方法分析了InGaN/GaN量子阱数量变化对双波长发光二极管发光光谱、内量子效率、电子空穴浓度分布、溢出电流等产生的影响.分析结果表明,量子阱数量的增加会引起载流子分配不均的现象,所以量子阱数量的增加并不能有效地提升载流子复合率、内量子效率和发光强度,还会引起开启电压升高的现象,影响能量转化效率.此外,不同发光波长的量子阱数量的增加会引起发光光谱强度的变化. 关键词： 量子阱 数量 数值模拟 双波长发光二极管     

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 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.     

The influence of AlGaN/GaN superlattices as electron blocking layers on the performance of blue InGaN light-emitting diodes

P-AlGaN/P-GaN superlattices are investigated in blue InGaN light-emitting diodes as electron blocking layers.The simulation results show that efficiency droop is markedly improved due to two reasons:(i) enhanced hole concentration and hole carrier transport efficiency in AlGaN/GaN superlattices,and(ii) enhanced blocking of electron overflow between multiple quantum-wells and AlGaN/GaN superlattices.     

Investigation of GaN-based dual-wavelength light-emitting diodes with p-type barriers and vertically stacked quantum wells

Designs of p-doped in quantum well (QW) barriers and specific number of vertically stacked QWs areproposed to improve the optical performance of GaN-based dual-wavelength light-emitting diodes (LEDs).Emission spectra, carrier concentration, electron current density, and internal quantum efficiency (IQE)are studied numerically. Simulation results show that the efficiency droop and the spectrum intensityat the large current injection are improved markedly by using the proposed design. Compared with the conventional LEDs, the uniform spectrum intensity of dual-wavelength luminescence is realized when aspecific number of vertically stacked QWs is adopted. Suppression of electron leakage current and the promotion of hole injection efficiency could be one of the main reasons for these improvements.     

Comparison of nitride-based dual-wavelength lightemitting diodes with an InAIN electron-blocking layer and with p-type doped barriers

The advantages of nitride-based dual-wavelength light-emitting diodes （LEDs） with an InA1N electron blocking layer （EBL） are studied. The emission spectra, carrier concentration in the quantum wells （QWs）, energy band and internal quantum efficiency （IQE） are investigated. The simulation results indicate that an LED with an InA1N EBL performs better over a conventional LED with an A1GaN EBL and an LED with p-type-doped QW barriers. All of the advantages are due to the enhancement of carrier confinement and the lower electron leakage current. The simulation results also show that the efficiency droop is markedly improved and the luminous intensity is greatly enhanced when an InAlN EBL is used.