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

摘要

In 535-565 nm green and deep green LED dies on c-planc sapphire, we correlate the structural morphology with photo-luminescence 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 initiaternV-defects that exhibit {1011} 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.