Performance Improvement of Red InGaN Micro-LEDs by Transfer Printing From Si Substrate Onto Glass Substrate

Abstract

Red micro light-emitting diodes (micro-LEDs) on silicon substrates are important components for realizing large-scale and low-cost micro-LED displays. Recently, InGaN red micro-LEDs have received enormous attention because their external quantum efficiency (EQE) is not significantly affected by size effect and they are compatible with existing green and blue LED material systems. Here, taking advantage of the easy removal of silicon substrates, we successfully achieved the transfer printing of InGaN red micro-LEDs. By removing the light-absorbing Si substrate and introducing a metal mirror, the transfer printed micro-LEDs exhibited better color purity, higher optical power, and higher EQE. At 0.5 A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , the optical power of micro-LEDs on glass was 300% higher than that of micro-LEDs on silicon. And the peak EQE of transfer printed micro-LEDs was 2.3 times that of micro-LEDs on native substrate. This work is applicable to most transfer printing techniques requiring PDMS stamps, and shows the potential to realize InGaN-based full-color micro-LED displays by mass transfer in the future.