Theoretical investigations for strain relaxation and growth mode of inas thin layers on gaas(111)a†

Abstract

The growth mode of InAs/GaAs(111)A is systematically investigated using our macroscopic theory with the aid of empirical potential calculations that determine parameter values used in the macroscopic theory. Here, stacking-fault tetrahedron (SFT) found in InAs/GaAs(111)A and misfit dislocation (MD) formations are employed as strain relaxation mechanisms. The calculated results reveal that the MD formation occurs at the layer thickness h about 7 monolayers (MLs). Moreover, we found that the SFT forming at h about 4 MLs makes surface atoms move upward to reduce the strain energy to promote the two dimensional (2D) growth. Therefore, the SFT in addition to the MD plays an important role in strain relaxation in InAs thin layers on GaAs(111)A. The macroscopic free energy calculations for the growth mode imply that the InAs growth on the GaAs(111)A proceeds along the lower energy path from the 2D-coherent (h ≤ 4 MLs) to the 2D-MD (h ≥ 7 MLs) via the 2D-SFT (4 MLs ≤ h ≤ 7 MLs). Consequently, the 2D growth on the InAs/GaAs(111)A results from strain relaxation due to the formation of the SFT near the surface and the subsequent MD formation at the interface.