OPTICAL PROPERTIES OF EPITAXIAL GA<sub>X</sub>IN<sub>1- X</sub>P SOLID SOLUTIONS WITH ATOMIC ORDERING
Using a set of spectroscopic methods, the properties of epitaxial Ga<sub>x</sub>In<sub>1-x</sub>P alloys with the ordered arrangement of the atoms in a crystal lattice grown by MOCVD on single-crystalline GaAs (100) substrates were studied. Based on the data of the dispersion analysis for IR reflection spectra and UV-spectroscopy data obtained in transmittance-reflection mode, the basic optical characteristics of the ordered Ga<sub>x</sub>In<sub>1-x</sub>P alloys were determined for the first time, i.e. dispersion of the refractive coefficient and high-frequency dielectric permeability. The study of the optical and photoluminescence properties of the ordered Ga<sub>x</sub>In<sub>1-x</sub>P alloys in the UV spectral range confirms previous data that the metal-organic chemical deposition of the vapors (MOCVD) not only gives rise to a strong CuPt-B type ordering, but also ensures a good uniformity of the film and its transmission capacity. A decrease in the band gap energy on the ordered Ga<sub>x</sub>In<sub>1-x</sub>P alloy determined in our experiments at the specified level of distortion and factor of the order is in good agreement with the theoretical data and similar experimental studies. Comparing the value of high-frequency dielectric permeability s<sub>m</sub> for the epitaxially ordered Ga<sub>x</sub>In<sub>1-x</sub>P alloys with that for the disordered alloys of the same composition x - 0.50 determined from the analysis of IR reflection spectra, it was shown for the first time that this parameter for the ordered alloy was 1.5-2 times higher. Also it was shown that the refractive index for the epitaxial films with ordering is 1.5-2.5 times higher than that for disordered values of the same composition x - 0.50. Moreover, the maximum value of refractive index for the sample with a high degree of order was n = 5.45 at the wavelength of-680 nm, while the close value for the disordered alloy with a similar composition of x - 0.50 was attained in the wavelengths in the range of - 330-340 nm.