Influence of tensile and compressive strain on the band gap energy of ordered InGaP

Abstract

The band gap energy of ordered and strained InxGa1−xP as a function of ternary composition was studied. Epitaxial growth using a metalorganic vapor phase epitaxy technique at a reactor pressure of 20 mbar and Tg=580 °C allowed us to prepare a set of samples with nearly constant ordering parameter η. Optical measurements were performed at room temperature using a rotating polarizer ellipsometer with a spectral energy range 1.4–5.1 eV. Comparing the experimental data with the theory, we have shown that the band gap energy Eg dependence on composition closely follows the prediction of Wei and Zunger [S. Wei and A. Zunger, Phys. Rev. B 49, 14337 (1994)]. This prediction is more valid as the commonly used parabolic interpolation of Eg between InP and GaP values.