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


Zhang Y., Jamal-Eddine Z., Akyol F. , Bajaj S., Johnson J. M. , Calderon G., ...Daha Fazla

APPLIED PHYSICS LETTERS, cilt.112, 2018 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 112 Konu: 7
  • Basım Tarihi: 2018
  • Doi Numarası: 10.1063/1.5017045
  • Dergi Adı: APPLIED PHYSICS LETTERS

Özet

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 x 10(-3) Omega cm(2) obtained at 1 kA/cm(2). 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/cm(2) was 54.4 W/cm(2), 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. Published by AIP Publishing.