Experimental studies of the effects of atomic ordering in epitaxial Ga$_{x}$In$_{1-x}$P alloys on their structural and morphological properties

The properties of epitaxial Ga$_{x}$In$_{1-x}$P alloys with an ordered arrangement of atoms in the crystal lattice are studied by a number of structural and microscopic methods. The alloys are grown by metal-organic chemical vapor deposition onto single-crystal GaAs(100) substrates. It is shown that, under conditions for the coherent growth of an ordered Ga$_{x}$In$_{1-x}$P alloy on a GaAs(100) substrate, atomic ordering results in radical modifications of the structural properties of the semiconductor compared to the properties of disordered alloys. Among these modifications are a change in the crystal-lattice parameter and, as a consequence, lowering of the crystal symmetry and the formation of two different types of surface nanorelief. With consideration for elastic strains, the parameters of Ga$_{x}$In$_{1-x}$P alloys with ordering as functions of the order parameter are calculated for the first time. It is shown that all experimental data are in good agreement with the developed theoretical concepts.