Surface Lattice Strain Relaxation at the Initial Stage of Heteroepitaxial Growth of InxGa1-xAs on GaAs by Molecular Beam Epitaxy

Abstract

The surface morphology, surface lattice parameter, and growth mechanism of epilayers during molecular beam epitaxy are investigated using a reflection high-energy electron diffraction observation system. The intensity and half width of diffraction streaks, together with the surface lattice parameter of InxGa1-xAs grown on (001)GaAs substrates are measured in situ. The growth of InxGa1-xAs is conducted under an As-stabilized growth condition. The Stranski-Krastanov growth mode is dominant at the initial stage of heteroepitaxy. The surface lattice parameters of InxGa1-xAs epilayers match those of GaAs below a critical thickness (hc), while they show an abrupt increase toward a bulk InxGa1-xAs lattice parameter beyond the hc value. The observed hc value almost coincides with the critical thickness for the transition of the growth mode from 2D to 3D.