Improvement in the Light Extraction of Blue InGaN/GaN-Based LEDs Using Patterned Metal Contacts
Statler College of Engineering and Mining Resources
Lane Department of Computer Science and Electrical Engineering
We demonstrate a method to improve the light extraction from an LED using photonic crystal (PhC)-like structures in metal contacts. A patterned metal contact with an array of Silicon Oxide (SiO x ) pillars (440 nm in size) on an InGaN/GaN-based MQW LED has shown to increase output illumination uniformity through experimental characterization. Structural methods of improving light extraction using transparent contacts or dielectric photonic crystals typically require a tradeoff between improving light extraction and optimal electrical characteristics. The method presented here provides an alternate solution to provide a 15% directional improvement (surface normal) in the radiation profile and ~ 30% increase in the respective intensity profile without affecting the electrical characteristics of the device. Electron beam patterning of hydrogen silesquioxane (HSQ), a novel electron beam resist is used in patterning these metal contacts. After patterning, thermal curing of the patterned resist is done to form SiO x pillars. These SiO x pillars aid as a mask for transferring the pattern to the p-metal contact. Electrical and optical characterization results of LEDs fabricated with and without patterned contacts are presented. We present the radiation and intensity profiles of the planar and patterned devices extracted using Matlab-based image analysis technique from 200 μm (diameter) circular unpackaged LEDs.
Digital Commons Citation
Kadiyala, Anand; Lee, Kyoungnae; Rodak, L E.; Hornak, Lawrence A.; Korakakis, Dimitris; and Dawson, Jeremy M., "Improvement in the Light Extraction of Blue InGaN/GaN-Based LEDs Using Patterned Metal Contacts" (2014). Faculty & Staff Scholarship. 2537.
Chen Yang, Yi-hao Wang, Yi Wang, Zhao Ding, Jun Wen, Li-Feng Bian, "Radiation Pattern Measurement in the Planar Coordinate", Photonics Journal IEEE, vol. 11, no. 6, pp. 1-10, 2019.