p-GaN/p-AlxGa1-xN异质结界面处二维空穴气的性质及其对欧姆接触的影响

通过自洽求解一维泊松方程和薛定谔方程,得到了p-GaN/p-Al_xGa_1-xN异质结界面处的价带结构和二维空穴气（2DHG）分布,研究了A1组分和压电极化效应对界面处2DHG性质的影响,给出了异质界面处2DHG的面密度、浓度分布以及价带结构.实验结果表明:随着Al组分的增加,异质结界面处势阱明显加深变窄,这使得2DHG的峰值密度加速上升,也使得面空穴密度近直线上升;压电极化效应也明显使界面处势阱加深变窄,并且使费米能级向势垒顶端移动,峰值浓度的位置向界面处移动;另外,价带带阶高度和受主杂质浓度对2DHG的影响较小.利用这层2DHG制作的p-Al_xGa_1-xN的欧姆接触,电流电压特性明显好于直接制作的电极,说明了2DHG可以显著改善p-Al_xGa_1-xN的欧姆接触性能.     

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.     

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.     

p-AlGaN电子阻挡层Al组分对Si衬底绿光LED性能影响的研究

在Si(111)衬底上利用MOCVD方法生长了具有不同Al组分p-AlGaN电子阻挡层的绿光InGaN/GaN LED结构,并对其光电性能进行了研究.结果表明,不同Al组分样品的量子效率随电流密度的变化规律呈现多样性.在很低电流密度范围,LED量子效率随Al组分升高而下降;在较高电流密度范围,LED量子效率随Al组分升高而升高,即此时缓解了量子效率随电流密度增大而衰退的速率(即droop效应);但随着电流密度的进一步升高,反而加快了量子效率衰退的速率.这些现象解释为不同Al组分的p-AlGaN对空穴和电子 关键词： 氮化镓 p-AlGaN 绿光LED 量子效率     

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）.     

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

In this study,the efficiency droop of an InGaN light-emitting diode(LED)is reduced significantly by using a pAlGaN/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).