Comment on "threshold for optically induced dislocation glide in GaAs-GaAlAs double heterostructures: Degradation via a new cooperative phenomenon?"

On scratching the surface of a GaAs-GaAlAs heterostructure grown without the usual capping layer and subsequently applying intense optical excitation, it has been found that a threading dislocation results which bows out into the bottom waveguide-active layer interface [Monemar et al., Phys. Rev. Lett. 41, 260 (1978)]. The question has subsequently arisen why the dislocation does not bow out into the active layer-top waveguide interface [Woolhouse et al., Appl. Phys. Lett. 33, 94 (1978)]. In this Comment an answer to this question is presented in terms of the expected minimum-energy configuration of dislocations in a three-layer structure. © 1981 The American Physical Society.