V‐defect analysis in green and deep green light emitting diode structures

Abstract

Abstract In 535‐565 nm green and deep green LED dies on c‐plane sapphire, we correlate the structural morphology with photoluminescence performance. Two classes of material with active region roughness of 4 nm and 0.4 nm (RMS) are analyzed in transmission electron microscopy. In the rough material, a high density of edge‐type dislocations is identified that originates within the quantum wells (QWs). They initiate V‐defects that exhibit {10 $ \bar 1 $ 1} growth facets with a second set of narrow QWs and barriers. As V‐defects widen with progressive growth, the width of QW and barriers on the c‐plane increases. In the smooth material, however, no V‐defects can be found. QWs and barriers are highly uniform and homogenous throughout the structure. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)