The new origin of dark-line defects in planar-stripe DH lasers

The transmission electron microscope (TEM) observations of degraded and undegraded diodes have shown that usually, though not always, small dislocation loops are introduced into the stripe area during selective zinc diffusion for stripe fabrication. These loops grow to giant dislocation loops, which correspond to dark line defects (DLD's) during device operation. The growth velocity of DLD's which originate from the loops with Burgers vectors of
a/2 \langle 011 \rangle
inclined is more rapid than that of
a [001]
normal and
a/2 \langle 110 \rangle
parallel to the junction plane, and is the same order of magnitude as the growth velocity of common DLD's which originate from the threading dislocations.