Origins of Parasitic Emissions from 353 nm AlGaN-based UV LEDs over SiC Substrates

Abstract

The effects of p-GaN capping layers and p-type carrier-blocking layers on the occurrence of parasitic emissions from 353 nm AlGaN-based LEDs have been investigated. LEDs without a ptype Al 0.25 Ga 0.75 N carrier-blocking layer showed a shoulder peak at ~370 nm due to electron overflow into the p-Al 0.10 Ga 0.90 N cladding layer and subsequent electron-hole recombination in the acceptor levels. Broad emission between 380 and 450 nm from LEDs having a p-GaN capping layer was caused by 420 nm luminescence from the p-GaN capping layer, which was optically pumped by 353 nm UV emission from the quantum wells. Broad, defect-related luminescence at ~520 nm was emitted from the AlGaN layers within the quantum wells. 0892-FF09-02.1 Mater. Res. Soc. Symp. Proc. Vol. 892