Atomic-scale imaging of strain relaxation via misfit dislocations in highly mismatched semiconductor heteroepitaxy: InAs/GaAs(111)A

Strain relaxation in InAs/GaAs(111)A heteroepitaxy has been studied on the atomic scale by scanning tunneling microscopy. The coalescence of small islands and the formation of a dislocation network are identified at the critical layer thickness (CLT), and no three-dimensional growth is observed, even beyond the CLT. The atomic displacement around the threading segments and the strain fields induced by the misfit dislocations are both identified. The measured density of the misfit dislocations indicates that the strain is not fully relaxed at the CLT, but is instead gradually relieved with the additional growth of InAs.