Substrate Lifted-off AlGaN/AlGaN Lateral Conduction Thin-Film Light-Emitting Diodes Operating at 285 nm

Abstract

We report on the substrate laser lift-off (LLO) in lateral conduction flip-chip (FC) deep-UV light-emitting diodes (LEDs) with peak emission wavelength at 285 nm. The AlGaN-based LED epilayer structure was grown on a low-defect 2 µm-thick AlN/sapphire template and processed into 3×3 small periphery pixel-LED arrays. The total p-contact area of the 9 pixel, single chip devices was 180 ×180 µm2. Our results show that the use of FC die assembly with epoxy underfilling the gap between the chip and the submount dramatically increase the yield of damage-free debonding of sapphire and the overlying AlN layer. Equally important, no noticeable degradation of the electrical and optical characteristics of the thin-film light emitters was observed following the LLO process.