Theoretical study for misfit dislocation formation at InAs/GaAs(001) interface

Abstract

The formation of misfit dislocations (MDs) at InAs/GaAs(001) interface is theoretically investigated using empirical interatomic potentials and ab initio calculations. The calculated cohesive energy using empirical interatomic potentials demonstrate that InAs/GaAs(001) system with 5/7 MD core structure is stabilized compared with coherently grown system when the thickness of InAs wetting layer is larger than 1 monolayer (ML). This result suggests that lattice strain is relaxed by incorporating MD to proceed the growth of InAs wetting layers. The estimated critical thickness of MD formation and dislocation formation energy for InAs/GaAs(001) are 0.5 ML and 1.51eV/Å, respectively, which are favorably compared with those of InAs/GaAs(110) interface. Using the calculated results of MDs by empirical interatomic potentials and surface energies by ab initio calculations, we furthermore evaluate growth modes of InAs on GaAs(001) substrate on the basis of macroscopic theories. The estimation of free energies reveals that two-dimensional growth with MDs and Stranski-Krastanov coherent growth simultaneously appear around 0.6 ML. These results suggest that the formation MDs at InAs/GaAs(001) interface is crucial for the wetting layer growth on GaAs(001) substrate.