AlGaN-based deep ultraviolet light emitting diodes with reflection layer

摘要

We report on the effect of reflection layer on electrical and optical characteristics of AlGaN-based multiple-quantum well deep-UV flip chip light-emitting diodes. Relatively thick Al metal as a reflector layer was deposited on the p-contact of deep-UV LEDs by e-beam evaporator at a nominal chamber pressure of 2 × 10~(-6) mtorr. AlGaN-based flip chip deep-UV LEDs using Ni/Au/Al/Ti/Au composite reflection layers exhibited a significant improvement in their optical output power and extraction efficiencies. Efforts have also been involved to improve the reflection properties of the packaged devices without increase their forward voltages. Present results suggest that, for efficient deep-UV flip chip LEDs, the deposited Al-reflection layer should have an optimal thickness of ≥ 200 nm.