Growth and propagation mechanism of 〈110〉-oriented dark-line defects in GaAs-Ga1−xAlxAs double heterostructure crystals

Abstract

Application of external stress on a double heterostructure (DH) crystal is used to induce 〈110〉‐oriented dark‐line defects (DLD). The stress is applied by using a four‐point mechanical bending apparatus. Resulting DLD formation is found to depend on stress direction and DH crystal orientation. This asymmetric DLD introduction can be explained by the difference in glide motion between α and β dislocations. It is shown that a threshold stress exists for the DLD formation. This threshold stress and the growth velocity of the DLD’s strongly depend on optical pump intensity. Extension of the DLD’s into the ternary passive layers is observed by x‐ray topography and phase‐contrast microscopy. This observation suggests that stresses caused by local heating at the site of a defect play an important role in inducing 〈110〉 DLD’s. These experimental results lead to the conclusion that dislocation glide processes are responsible for 〈110〉‐DLD propagation.