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Tunnel-injected sub 290 nm ultra-violet light emitting diodes with 2.8% external quantum efficiency

2018; American Institute of Physics; Volume: 112; Issue: 7 Linguagem: Inglês

10.1063/1.5017045

1520-8842

Yuewei Zhang, Zane Jamal-Eddine, Fatih Akyol, Sanyam Bajaj, Jared M. Johnson, Gabriel Calderon, Andrew A. Allerman, Michael W. Moseley, Andrew Armstrong, Jinwoo Hwang, Siddharth Rajan,

Ga2O3 and related materials

We report on the high efficiency tunnel-injected ultraviolet light emitting diodes (UV LEDs) emitting at 287 nm. Deep UV LED performance has been limited by the severe internal light absorption in the p-type contact layers and low electrical injection efficiency due to poor p-type conduction. In this work, a polarization engineered Al0.65Ga0.35N/In0.2Ga0.8N tunnel junction layer is adopted for non-equilibrium hole injection to replace the conventionally used direct p-type contact. A reverse-graded AlGaN contact layer is further introduced to realize a low resistance contact to the top n-AlGaN layer. This led to the demonstration of a low tunnel junction resistance of 1.9 × 10−3 Ω cm2 obtained at 1 kA/cm2. Light emission at 287 nm with an on-wafer peak external quantum efficiency of 2.8% and a wall-plug efficiency of 1.1% was achieved. The measured power density at 1 kA/cm2 was 54.4 W/cm2, confirming the efficient hole injection through interband tunneling. With the benefits of the minimized internal absorption and efficient hole injection, a tunnel-injected UV LED structure could enable future high efficiency UV emitters.