深紫外type-II量子阱的能带工程及与表面等离激元耦合的研究

III-nitride based deep-ultraviolet (DUV) light-emitting diode (LED) has attracted more and more attention due to a wide variety of potential applications, such as sterilization, water purification, polymer curing. However, the external quantum efficiency of nitride DUV LED is typically lower than ~10% due to the high dislocation density, the low hole concentration, and the low light extraction efficiency. In the study, we will employ the structure design strategy and surface-plasmon (SP) coupling to improve the performance of DUV LED in the 240nm to 280nm spectral range. First, we will design the type-II quantum well (QW) structure, and investigate its band structures and optical properties by the effective mass theory. Next, the energy transfer process of type-II QW-metal coupling will be numerically investigated by 6×6 K-P method taking into account the electron-hole band structures, the photon density of states of surface-plasmon-polariton (SPP), and the evanescent fields of SPP. Then, by the finite-difference time-domain (FDTD) method, we will simulate the steady-state electric field distribution, Purcell factor, absorption and scattering spectra of metal nanostructure in order to obtain a metal nanostructure with the lower energy loss and the effective SP-QW coupling. Finally, based on the research results of this subject, a visual and graphical program for calculating the band structure and optical properties of nitride LED will be written.

III族氮化物基深紫外LED在灭菌、水净化、聚合物固化等领域有着广阔的应用前景，吸引了越来越多的研究者关注和重视。尽管如此，由于高位错密度、低空穴浓度、低抽取效率等，氮化物深紫外LED的外量子阱效率普遍低于10%。本课题拟采用结构设计策略及表面等离激元（SP）耦合来改善波长在240-280nm范围的深紫外LED性能。首先设计type-II排列的量子阱结构，利用有效质量理论研究其能带结构及光学性质；其次，基于6×6 K-P方法，并考虑表面等离激元的态密度和瞬逝场，数值模拟type-II量子阱与金属耦合的能量转移过程；然后，利用时域有限差分 (FDTD)方法模拟金属纳米结构的静态场分布、Purcell因子、吸收和散射谱等，获得即能与深紫外LED有效地耦合又具有较低能量耗散的金属纳米结构；最后，基于本课题的研究成果，编写能方便地计算氮化物LED的能带结构及光学性质的可视化的、图形化的程序。

III族氮化物深紫外LED器件在灭菌、水净化、聚合物固化等领域有着广阔的应用前景，吸引了越来越多的研究者关注和重视。本课题主要研究了结构设计及表面等离激元 (SP) 耦合对于提高深紫外LED的发光效率的作用。首先，设计了两种type-II型量子阱 (QW) 结构LED器件。与传统结构相比，其TE偏振总自发发射率最高可提高105%。然后，研究了AlGaN基LED的光学偏振特性，并设计了一种耦合薄阱层结构，其既可增加器件的内量子效率，又可显著地抑制效率下降效应。其次，通过Al平面结构、Al纳米颗粒结构、Al纳米光栅结构，分析和研究了QW-SP耦合的能量转移过程及光抽取效率；其中Al纳米光栅结构的深紫外LED的输出谱线的峰值强度可提高70.3%。最后，基于K-P方法，编写了计算氮化物LED能带结构及其光学性质的具有图形用户界面的程序（即，III-族氮化物发光器件仿真软件V1.0）。