On the Γ-Γ and Γ-X transitions of the GaxIn1−xP alloys

The temperature dependence of $E_{\mathrm{\Gamma \Gamma }}{\mathrm{=\Gamma }}_6^c{\mathrm{-\Gamma }}_8^{\nu }$ is studied by piezoreflectance from 8 to 300°K. The variation is linear from 100 to 300°K with a temperature coefficient β=(−4.6±0.4) × 10⁻⁴ eV/°K for x =0.51. At low temperature the bowing parameter of the parabolic variation of E_ΓΓ vs x is 0.42 eV. At room temperature, electroreflectance measurements give 0.49 eV. The $X_6^c{\mathrm{-\Gamma }}_8^{\nu }$ indirect gap is measured by electrotransmission. At room temperature the Γ‐X crossover composition is x_c =0.63±0.02 and the corresponding energy E_ΓΓ= E_Γx=2.14±0.01 eV. For T < 10°K, x_c =0.69±0.02 and E_ΓΓ=E_Γx=2.32±0.01 eV.