Cathodoluminescence evaluation of dark spot defects in InP/InGaAsP light-emitting diodes

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Abstract
In this study, the formation of dark spot defects (DSD’s) in InP/InGaAsP light‐emitting diodes (LED’s) is evaluated by cathodoluminescence imaging and energy dispersive x‐ray spectroscopy (EDS). Defects resulting in DSD’s are shown to be located in either the p‐InGaAsP contact layer, the p‐InP confining layer, or the InGaAsP active layer. The presence of gold was not detected at the DSD’s using EDS. However, gold was found in the form of submicron‐sized inclusions in the contact layer and confining layer of cylindrically lapped wafers using EDS. Our results strongly suggest that the migration of gold from the p contact during device processing and aging results in the formation of DSD’s in InP/InGaAsP LED’s.