Tunnel-injected sub-260nm ultraviolet light emitting diodes

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Zhang Y., Krishnamoorthy S., Akyol F., Bajaj S., ALLERMAN A. A., MOSELEY M. W., ...More

APPLIED PHYSICS LETTERS, vol.110, no.20, 2017 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 110 Issue: 20
  • Publication Date: 2017
  • Doi Number: 10.1063/1.4983352
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Yıldız Technical University Affiliated: No


We report on tunnel-injected deep ultraviolet light emitting diodes (UV LEDs) configured with a polarization engineered Al0.75Ga0.25 N/In0.2Ga0.8N tunnel junction structure. Tunnel-injected UV LED structure enables n-type contacts for both bottom and top contact layers. However, achieving Ohmic contact to wide bandgap n-AlGaN layers is challenging and typically requires high temperature contact metal annealing. In this work, we adopted a compositionally graded top contact layer for non-alloyed metal contact and obtained a low contact resistance of rho(c) = 4.8 x 10(-5) Omega cm(2) on n-Al(0.75)G(a0.25)N. We also observed a significant reduction in the forward operation voltage from 30.9V to 19.2V at 1 kA/cm(2) by increasing the Mg doping concentration from 6.2 x 10(18) cm(-3) to 1.5 x 10(19) cm(-3). Non-equilibrium hole injection into wide bandgap Al0.75Ga0.25N with Eg>5.2 eV was confirmed by light emission at 257 nm. This work demonstrates the feasibility of tunneling hole injection into deep UV LEDs and provides a structural design towards high power deep-UV emitters. Published by AIP Publishing.