TEM Observation of Dark Defects Appearing in InGaAsP/InP Double-Heterostructure Light Emitting Diodes Aged at High Temperature

Dark defects which appear during high temperature aging of InGaAsP/InP 1.27 µm double-heterostructure light emitting diodes, were investigated by transmission electron microscopy and energy dispersive X-ray spectroscopy. Dark-spot defects are often observed in the electro-luminescent patterns of aged diodes, while cross-shaped <100> dark-line defects are rarely observed. The dark-spot defects, which correspond to bar-shaped precipitates, are thought to be generated by the precipitation of the host atoms during operation at certain nucleation centers. The cross-shaped dark-line defects, which are associated with complicated defects consisting of small dislocation clouds and fibrous edge-like dislocations, are thought to be generated by local melting at In and/or P rich inclusions.