Dislocations and Precipitates in GaAs Injection Lasers

Abstract

The new A-B etchant has been employed to reveal interfacial dislocations near the junctions of GaAs injection lasers. Injection lasers were examined parallel and perpendicular to the junction region. Dislocations are seen predominantly in the junction region, lying in the (001) plane, and in only two directions, the [110] and [11̄0]. Their source is ascribed to the lattice mismatch between the substrate and grown layer. Decoration of the dislocations parallel to [110] is observed, but very little decoration of the [11̄0] dislocations is seen. The decorating impurity is believed to be Zn. The difference in decoration of the [110] and [11̄0] dislocations is accounted for by a difference in the structure of these two dislocations. A direct correlation between lasing filaments and decorated interfacial dislocations was found in the [110] direction. This is believed to be due to the local distortion of the current lines near the defects.