Transfer Printed, Vertical GaN-on-Silicon Micro-LED Arrays With Individually Addressable Cathodes

• Published in: IEEE transactions on electron devices Vol. 69; no. 10; pp. 5630 - 5636
• Main Authors: Li, Changhao, Pan, Zhangxu, Guo, Chan, Li, Yuzhi, Zhou, Yue, Wang, Jiantai, Zou, Shenghan, Gong, Zheng
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.10.2022; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Backplanes; Cathodes; Electrodes; Flip-chip bonding; Indium; Indium base alloys; Light emitting diodes; Melting points; microdisplays; Optical imaging; Printing; Silicon; Substrates; transfer printing; vertical microscale light-emitting diodes (LEDs)
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2022.3202152

Microscale light-emitting diodes (Micro-LEDs) have attracted intensive research attention due to their potential applications in high-resolution displays, wearables, and VR/AR headsets. However, their device performance can be compromised by the common Micro-LED lateral structure, usually with both two electrodes facing toward the p-side. Here, we developed printable, silicon-based vertical Micro-LEDs with two electrodes facing oppositely, which showed better heat dissipation, and were 60% brighter over conventional lateral Micro-LEDs. We further developed a novel double-tape-assisted transfer process, which allowed these vertical Micro-LEDs to be transferred completely to a polyimide tape in a simple yet reliable manner. Combined with a bonding scheme based on low-melting-point-patterned indium alloys, these printed Micro-LEDs on the tape can be further integrated onto silicon backplanes with a shared p-contact. Followed by forming an individual n-electrode connected to each pixel, a novel-inverted, vertical microdisplay prototype device with individually addressing cathodes was demonstrated for the first time.