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.     

反对称n-AlGaN层对GaN基双蓝光波长发光二极管性能的影响

采用数值分析方法对在InGaN/GaN混合多量子阱活性层和n-GaN之间引入n-AlGaN层的GaN基双蓝光波长发光二极管进行模拟分析.结果发现,与传统的具有p-AlGaN电子阻挡层的双蓝光波长发光二极管相比,这种反对称n-AlGaN层能有效改善电子和空穴在混合多量子阱活性层中的分布均匀性及减少电子溢出,实现电子空穴在各个量子阱中的平衡辐射,从而减弱了双蓝光波长发光二极管的效率衰减.此外,通过改变Al组分可以提高双蓝光波长发光二极管发射光谱的稳定性:当Al组分为0.16时,双蓝光波长发光二极管的光谱在小电流下比较稳定,而Al组分为0.12时,光谱在大电流下比较稳定.     

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.     

金属有机化学气相淀积技术制备GaMnN薄膜材料光学性质研究

研究由MOCVD 技术制备的 GaMnN 外延薄膜光吸收谱.实验发现Mn掺杂后较未掺杂GaN吸收系数在近紫外区增加,在吸收谱低能区144 eV附近观察到吸收峰,吸收系数随Mn浓度的增加而增大.实验结果与基于密度泛函理论的第一性原理计算结果一致,结合理论计算分析认为144 eV附近的吸收峰源于Mn³⁺离子e态与t₂态间的带内跃迁⁵T₂→⁵E. 关键词： GaMnN MOCVD 密度泛函理论 光学性质     

Improved light extraction of GaN-based light-emitting diodes with surface-textured indium tin oxide electrodes by nickel nanoparticle mask dry-etching

GaN-based light-emitting diodes (LEDs) with surface-textured indium tin oxide (ITO) as a transparent current spreading layer were fabricated.The ITO surface was textured by inductively coupled plasma (ICP) etching technology using a monolayer of nickel (Ni) nanoparticles as the etching mask.The luminance intensity of ITO surface-textured GaN-based LEDs was enhanced by about 34% compared to that of conventional LED without textured ITO layer.In addition,the fabricated ITO surface-textured GaN-based LEDs would present a quite good performance in electrical characteristics.The results indicate that the scattering of photons emitted in the active layer was greatly enhanced via the textured ITO surface,and the ITO surface-textured technique could have a potential application in improving photoelectric characteristics for manufacturing GaN-based LEDs of higher brightness.     

Gax In1-xP缓冲层组分对InP自组装形貌影响的研究

应用缓冲层对自组装结构的作用能Er和自组装结构表面能E8 的协同作用分析了InP自组装结构在GaxIn1-xP缓冲层表面的形貌变化.计算发现缓冲层组分影响自组装结构的形貌.随着缓冲层与InP自组装结构之间应力的增加,InP岛倾向于拉长.理论计算还发现随着自组装结构体积的增大,自组装结构也随之拉长.而且缓冲层的参数决定了自组装结构最小能量状态时的体积大小.应用金属有机物化学气相沉积技术在GaAs衬底上生长了不同的InP/GaInP体系,并对实验得到的自组装体系形貌进行了分析.实验结果证实了以上的理论分析.     

Efficiency enhancement of an InGaN light-emitting diode with a p-AIGaN/GaN superlattice last quantum barrier

In this study, the efficiency droop of an InGaN light-emitting diode （LED） is reduced slgnlncanUy oy using a p-AlGaN/GaN superlattice last quantum barrier. The reduction in efficiency droop is mainly caused by the decrease of electron current leakage and the increase of hole injection efficiency, which is revealed by investigating the light currents, internal quantum efficiencies, energy band diagrams, carrier concentrations, carrier current densities, and radiative recombination efficiencies of three LED structures with the advanced physical model of semiconductor device （APSYS）.     

量子阱数变化对InGaN/GaN发光二极管瞬态响应的影响

理论上研究了当InGaN发光二极管(LED)有源区的量子阱数变化时,LED的大信号瞬态响应特性与这种变化的关系.结果来自于LED等效电路模型的SPICE模拟,模型参数的确定通过拟合已测量的LED的实验数据及模拟结果来实现.结果表明,LED光脉冲的上升时间随量子阱数的增加而增加,由3个量子阱构成的有源区是LED的优化结构.     

纤锌矿BexZn1-xO合金能隙弯曲系数的第一原理研究

采用密度泛函理论框架下的第一性原理平面波超软赝势方法, 对纤锌矿Be_xZn_1-xO合金进行能隙特性、弯曲系数和结构参数的计算. 结果表明: Be_xZn_1-xO合金的能隙和弯曲系数都随Be掺杂组分的增大而增大. 通过修正Be_xZn_1-xO合金的能隙值得知其合金弯曲系数b为6.02 eV, 这与实验值接近. 纤锌矿Be_xZn_1-xO合金的能隙弯曲系数过大主要来源于体积形变和电荷转移的贡献. 文中还分析了Be_xZn_1-xO合金的晶格常数、 平均键长和平均次近邻原子距离与Be组分的关系.     

纤锌矿型量子级联激光器的界面与受限声子比较

利用传输矩阵方法对纤锌矿型量子级联激光器有源区的界面与受限声子进行了研究.计算结果显示:在纵光学频域有一组界面声子与二组受限声子存在,而且最低频率的两个界面声子在一定条件下能转变为受限模式.通过比较界面声子与受限声子的色散及声子势发现两者有很大不同,且计算电声散射速率可以发现由这两种声子引起的散射率是可比拟的.