Lattice relaxation of AlGaAs layers grown on GaAs(100) substrate plane by organometallic vapor phase epitaxy

Abstract

In order to investigate the behavior of AlxGa1−xAs lattice relaxation caused by opposite directions of biaxial stress, i.e., tensile or compressive stress, AlxGa1−xAs (X=0–0.45) layers were grown on undoped and heavily In-doped GaAs substrates by organometallic vapor phase epitaxy. Al0.45Ga0.55As layers on undoped GaAs substrates are subject to biaxial compressive stress and have a large coherent length. Al0.3Ga0.7As layers grown on heavily In-doped GaAs substrates with a lattice constant larger by about 0.1% than that of undoped GaAs are subject to biaxial tensile stress and have much smaller coherent length. Furthermore, it is found that the coherent length depends on the growth temperature and that an increase in coherent length is brought in by the introduction of even a small amount of Al in the layers.