The light extraction efficiency (LEE), external quantum efficiency (EQE), and current–voltage characteristics of deep ultraviolet light emitting diodes (DUV-LEDs) with different aluminum mole fractions in the p-AlGaN layers have been investigated. Optimizing the p-AlGaN layer composition requires a tradeoff between reducing the absorption losses and limiting the increases in the p-contact resistance and operation voltage. AlGaN multiple quantum well LEDs emitting around 263 nm with different AlGaN:Mg short period super lattices (p-SPSL) ranging from x = 33% (UV-absorbing) to x = 68% (UV-transparent) average aluminum mole fraction have been explored. DUV-LEDs with different p-contact metals and UV-reflectivities have been characterized by electroluminescence measurements and analyzed by ray-tracing simulations. The comparison shows an increased operating voltage and a five-fold increase of the on-wafer EQE with a maximum value of 3.0% for DUV-LEDs with UV-transparent p-SPSL (x = 68%) and UV-reflective indium contacts in comparison to LEDs with a UV-absorbing p-SPSL (x = 33%). Ray-tracing simulations show that the increase in EQE can be partially ascribed to a 2.5-fold improved LEE in combination with a two-fold increase in internal quantum efficiency.

研究了 p-AlGaN 层中具有不同铝摩尔分数的深紫外发光二极管 (DUV-LED) 的光提取效率 (LEE)、外量子效率 (EQE) 和电流-电压特性。优化 p-AlGaN 层成分需要在降低吸收损耗和限制 p 接触电阻和工作电压的增加之间进行权衡。AlGaN 多量子阱 LED 发射波长约为 263 nm，具有不同的 AlGaN:Mg 短周期超晶格 (p-SPSL)，范围从x = 33%（吸收紫外线）到x= 68%（紫外线透明）平均铝摩尔分数已被探索。具有不同 p 接触金属和紫外线反射率的 DUV-LED 已通过电致发光测量进行表征，并通过光线追踪模拟进行分析。比较显示，对于具有紫外线透明 p-SPSL ( x = 68%) 和紫外线反射铟触点的DUV-LED，工作电压增加了五倍，晶圆上 EQE 增加了 5 倍，最大值为 3.0% 。与具有吸收紫外线的 p-SPSL ( x = 33%) 的LED 进行比较。光线追踪模拟表明，EQE 的增加部分归因于 LEE 提高了 2.5 倍，同时内部量子效率提高了两倍。