Strained layer growth of Ga1-xInxP on GaAs (100) and GaP (100) substrates

We have investigated by Reflection High Energy Electron Diffraction (RHEED) the relaxation of strained Ga1-xInxP layers grown by Gas Source Molecular Beam Epitaxy (GSMBE) on GaAs (100) and GaP (100) substrates. We show that f or tensile layers grown on GaAs at 520 degrees C, the 2D-3D growth mode tra nsition occurs around 3-4 monolayers (ML) when the In content reaches 30%. i.e. for a lattice mismatch of 1.4%. This abnormal behavior is nor observed when compressive layers are grown on GaP at 520 degrees C for the same mis match magnitude. We discuss this difference taking into account the composi tion and temperature ranges for which spinodal decomposition of Ga1-xInxP a lloys have been predicted together with the strain sign. (C) 2000 Elsevier Science B.V. All rights reserved.