Effect of the sign of misfit strain on the dislocation structure at interfaces of heteroepitaxial GaAsxP1−x films

Abstract

It was shown, with the use of transmission electron microscopy, that the dislocation structure at interfaces of heteroepitaxial GaAsxP1−x films is dependent on the sign of the misfit strain. Under tensile strain the interface contains a square grid network of both perfect and partial misfit dislocations. The dislocations are straight and exist predominantly along 〈110〉 directions. This configuration of misfit dislocations is consistent with the nucleation of partial dislocations in tensile strained films. The compressive interface also contains a network of misfit dislocations many of which have curved segments. This indicates that a cross slip mechanism has occurred that is only possible with a perfect dislocation movement. This result supports the nucleation of perfect dislocations in films under a compressive strain. The different structural characteristics of the tensile and compressive systems can play a significant role in subsequent processing or devices made from them.