Wafer-scale transfer route for top\u2013down III-nitride nanowire LED arrays based on the femtosecond laser lift-off technique

Nursidik Yulianto,Alina Syring,Nurhalis Majid,Patrick Schnell,Kuwat Triyana,Florian Meierhofer,Tobias Voss,Andam Deatama Refino,Shinta Mariana,Hutomo Suryo Wasisto,Fatwa F Abdi,Andreas Waag,Ruri Agung Wahyuono,Winfried Daum

doi:10.1038/s41378-021-00257-y

Abstract

The integration of gallium nitride (GaN) nanowire light-emitting diodes (nanoLEDs) on flexible substrates offers opportunities for applications beyond rigid solid-state lighting (e.g., for wearable optoelectronics and bendable inorganic displays). Here, we report on a fast physical transfer route based on femtosecond laser lift-off (fs-LLO) to realize wafer-scale top–down GaN nanoLED arrays on unconventional platforms. Combined with photolithography and hybrid etching processes, we successfully transferred GaN blue nanoLEDs from a full two-inch sapphire substrate onto a flexible copper (Cu) foil with a high nanowire density (~107 wires/cm2), transfer yield (~99.5%), and reproducibility. Various nanoanalytical measurements were conducted to evaluate the performance and limitations of the fs-LLO technique as well as to gain insights into physical material properties such as strain relaxation and assess the maturity of the transfer process. This work could enable the easy recycling of native growth substrates and inspire the development of large-scale hybrid GaN nanowire optoelectronic devices by solely employing standard epitaxial LED wafers (i.e., customized LED wafers with additional embedded sacrificial materials and a complicated growth process are not required).

Highlights

Gallium nitride (GaN) has been continuously used in the light-emitting diode (LED) industry for almost three decades since the introduction of commercial high-brightness gallium nitride (GaN) blue LEDs in 1993 by Nakamura et al.[1,2,3]
GaN microLEDs grown on sapphires are commonly flip-chip bonded onto silicon-based complementary metal oxide semiconductor (CMOS) drivers, in which a laser lift-off
In this work, we investigated the potency of femtosecond laser lift-off (fs-laser lift-off (LLO)) to transfer wafer-scale GaN nanoLEDs embedded in SU-8 from a sapphire substrate onto a Cu foil, in which commercial GaN LED wafers were used during laser processing

Summary

Introduction

Gallium nitride (GaN) has been continuously used in the light-emitting diode (LED) industry for almost three decades since the introduction of commercial high-brightness GaN blue LEDs in 1993 by Nakamura et al.[1,2,3]. For state-of-the-art LLO-based transfer technology in the LED industry, various short-pulsed laser sources (e.g., excimer and Q-switched nanosecond lasers (355 nm)) have frequently been used, where delamination of the GaN layer from the sapphire occurs based on a direct photon absorption mechanism in the n-GaN part located at the GaN/sapphire interface[16]. This technological concept is mature and generally used in LED fabrication

Methods

Results

Conclusion