Improved Light Output Power of 16 × 16 Pixelated Micro-LEDs for Headlights by Enhancing the Reflectivity and Coverage of the p-Electrode

Tae Kyoung Kim, Moon Uk Cho, Jae Min Lee, Yu Jung Cha, Seung Kyu Oh, Bikramjit Chatterjee, Jae Hyun Ryou, Sukwon Choi, Joon Seop Kwak

Research output: Contribution to journalArticlepeer-review

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Abstract

A pixel array of micro-light emitting diodes (µ-LEDs) based on a flip-chip structure and driven by a passive matrix is fabricated. The array is fabricated through multi-level metallization using a photosensitive polyimide (PSPI) inter-metal dielectric (IMD) layer. The device consisted of 256 pixels in a 2 × 2 mm2 array (the individual pixel area is 115 × 115 µm2). This device facilitates the control of individual µ-LEDs in the array. To investigate the effect of reflectivity and coverage to p-GaN on mesa area of p-type electrode, controlled and uncontrolled µ-LED arrays is fabricated with different reflectivity and coverage of the p-type electrode. The results show that the devices has similar electrical properties. The light output power and maximum electroluminescence intensity of the controlled µ-LED array is improved by 3.7 and 5.1 times at injection currents of 100 and 60 mA compared to the uncontrolled µ-LED array, respectively. The variation of dark spaces in several emission images (total 9 pixels) is investigated as a function of the pixel pitch for the controlled µ-LED array at an injection current of 20 mA. The results shows that the dark space between pixels almost disappears at a pixel pitch of 125 µm.

Original languageEnglish (US)
Article number1700571
JournalPhysica Status Solidi (A) Applications and Materials Science
Volume215
Issue number10
DOIs
StatePublished - May 23 2018

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Electrical and Electronic Engineering
  • Materials Chemistry

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