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

The band gap energy of ordered and strained InxGa1-xP as a function of tern ary composition was studied. Epitaxial growth using a metalorganic vapor ph ase epitaxy technique at a reactor pressure of 20 mbar and T-g=580 degreesC allowed us to prepare a set of samples with nearly constant ordering param eter eta. Optical measurements were performed at room temperature using a r otating polarizer ellipsometer with a spectral energy range 1.4-5.1 eV. Com paring the experimental data with the theory, we have shown that the band g ap energy E-g dependence on composition closely follows the prediction of W ei and Zunger [S. Wei and A. Zunger, Phys. Rev. B 49, 14337 (1994)]. This p rediction is more valid as the commonly used parabolic interpolation of E-g between InP and GaP values. (C) 2001 American Institute of Physics.