Surface Lattice Strain Relaxation at the Initial Stage of Heteroepitaxial Growth of In_xGa_1-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 In x Ga 1- x As grown on (001)GaAs substrates are measured in situ . The growth of In x Ga 1- x As 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 In x Ga 1- x As epilayers match those of GaAs below a critical thickness ( h c ), while they show an abrupt increase toward a bulk In x Ga 1- x As lattice parameter beyond the h c value. The observed h c value almost coincides with the critical thickness for the transition of the growth mode from 2D to 3D.