Reverse-bias electroluminescence imaging to diagnose failures of vertical-cavity surface-emitting lasers

The charge flowing through the junction of vertical-cavity surface-emitting lasers (VCSELs) under reverse-bias gives rise to electroluminescence (EL) when breakdown conditions are satisfied. We collected the reverse-bias EL of VCSEL devices that had been subjected to accelerated stress. We observed distinctly different spatial distributions of the reverse-bias EL: for survivor (nondegraded) devices the breakdown current appears to be confined to one well-defined filament while for dark (degraded) VCSELs the reverse-bias EL pattern is a disordered network of filaments. We show that the line dislocation network that renders the VCSELs dark is directly imaged as the spatial distribution of the reverse-bias EL. (c) 2005 American Institute of Physics.