Plasma‐Damage Free Efficiency Scaling of Micro‐LEDs by Metal‐Assisted Chemical Etching

Abstract

Since its inception, LEDs have slowly transitioned from traditional solid‐state lighting applications to full‐color, self‐emissive displays. Micro‐LEDs (µLEDs) are poised to become the next mass‐market technology for displays in lower pixel‐density, large‐area and mobile devices alongside emerging applications for high pixel‐density augmented, virtual and mixed reality. However, it is well known that µLEDs suffer from efficiency cliff – a drastic efficiency reduction as device dimension reduces with increased severity at the single digit micron scale, often attributed to material damage from reactive ion etching (RIE) that is fundamental to the process. In this paper, a first‐ever demonstration of µLED devices ranging from 45 µm down to 5 µm fabricated by the plasma‐free metal‐assisted chemical etching (MacEtch) is presented. These devices demonstrate converging external quantum efficiencies (EQE) irrespective of mesa dimension with a spread of only 3.7% without optimization. Additionally, a multi‐pronged comparison between MacEtch and RIE is provided in terms of smoothness, material damage, macroscale uniformity and throughput. These findings carry profound implications for damage‐free scaling of multi‐heterojunction III‐V optoelectronic devices, providing a pathway for high‐density, high performance top‐down fabricated µLED arrays.

Metal-assisted chemical etching beyond Si: applications to III–V compounds and wide-bandgap semiconductors

“…Chan et al 112 studied the feasibility of GaN blue-light emitting diodes defined via Ru-catalyzed MacEtch. Due to the poor selectivity of p-type MacEtch of GaN 38 and better electrical and optical characteristics for p-doped topside in optical p-n devices, 114 the surficial p-region of the LED was first etched via RIE, and the resulting III-N active and n-doped regions were etched with a MacEtch process utilizing K 2 S 2 O 8 and HCl.…”