Flexible arrays of GaN-based Micro-LEDs fabricated on different substrates by a laser lift-off process

Abstract

Fabrication of flexible Micro-LEDs is becoming an important technology for flexible displays, which plays a significant role in the field of visual communication in the upcoming Internet-of-Things era and metaverse. Here, we explore high-quality laser lift-off (LLO) methods for gallium nitride (GaN)-based Micro-LED arrays using LLO technology to separate Micro-LED arrays from sapphire substrates via a KrF excimer laser system (λ = 248 nm). At the same time, the damage of GaN under high laser energy density was analyzed. Ultimately, we used viscoelastic stamp transfer technology to successfully transfer Micro-LED arrays to various types of substrates, including tape and copper foil (Cu), thus enabling applications in different scenarios. The results show that the threshold voltage and electroluminescence (EL) intensity of Micro-LEDs on the tape and Cu substrates increased slightly, and the peak of the EL spectrum was basically stable at 458 nm. Furthermore, Micro-LEDs on polyethylene terephthalate (PET) can still work normally when the bending radius of PET is 4 cm.