Experimental investigations of atomic ordering effects in the epitaxial Ga_xIn_1-xP, coherently grown on GaAs (100) substrates

A range of structural and spectroscopic techniques were used for the study of the properties of epitaxial Ga_xIn_1-xP alloys with an ordered arrangement of atoms in a crystal lattice grown by MOCVD on single-crystalline substrates of GaAs (100). The appearance of atomic ordering in the coherent growth conditions of the ordered Ga_xIn_1-xP alloy on GaAs (100) resulted in cardinal changes of the structural and optical properties of semiconductor in comparison to disordered alloys, including the change of the crystal lattice parameter and, consequently, reduced crystal symmetry, decreased band gap and formation of two different types of surface nanorelief. This is the first report of the calculation of parameters of the crystal lattice in Ga_xIn_1-xP with ordering taking into account the elastic stresses dependent on long-range ordering. Based on the variance analysis data with regard to the IR-reflection spectra as well as the UV-spectroscopy data obtained in the transmission-reflection mode, the main optical characteristics of the ordered Ga_xIn_1-xP alloys were determined for the first time, namely, refractive index dispersion and high-frequency dielectric constant. All of the experimental results were in good agreement with the previously developed theoretical beliefs.