The disinfection industry would greatly benefit from efficient, robust, high-power deep-ultraviolet light-emitting diodes (UV–C LEDs). However, the performance of UV–C AlGaN LEDs is limited by poor light-extraction efficiency (LEE) and the presence of a large density of threading dislocations. We demonstrate high power AlGaN LEDs grown on SiC with high LEE and low threading dislocation density. We employ a crack-free AlN buffer layer with low threading dislocation density and a technique to fabricate thin-film UV LEDs by removing the SiC substrate, with a highly selective SF6 etch. The LEDs (278 nm) have a turn-on voltage of 4.3 V and a CW power of 8 mW (82 mW/mm2) and external quantum efficiency (EQE) of 1.8% at 95 mA. KOH submicron roughening of the AlN surface (nitrogen-polar) and improved p-contact reflectivity are found to be effective in improving the LEE of UV light. We estimate the improved LEE by semiempirical calculations to be 33% (without encapsulation). This work establishes UV LEDs grown on SiC substrates as a viable architecture to large-area, high-brightness, and high-power UV LEDs.
|Original language||English (US)|
|State||Published - Jan 27 2020|
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: This work was funded by KACST-KAUST-UCSB Solid State Lighting Program (SSLP), part of the Technology Innovations Center programs at King Abdulaziz City for Science and Technology (KACST) and King Abdullah University of Science and Technology (KAUST). Also, it was funded by the support of the Solid State Lighting and Energy Electronics Center (SSLEEC) at UCSB and the UCSB-Collaborative
Research in Engineering, Science, and Technology (CREST) Malaysia Project. A portion of this work was conducted in the UCSB nanofabrication facility, NSF NNIN network (ECS0335765), as well as the UCSB MRL, which is supported by the NSF MRSEC Program (DMR05-20415). This work was also supported by the National Science Foundation Graduate Research Fellowship Program (Grant No. 1650114). The authors would like to thank the clean room staff at UCSB nanofabrication facility, and Tal Margalith and Claude Weisbuch for useful discussions.