Temperature dependencies of the refractive index for Al-Ga-In-As metamorphic layers

Temperature dependencies of the refractive indices, n, for In_xGa_1-As and In_xAl_1-As metamorphic layers with x=0.06-0.25 have been determined. For this purpose, we performed variable-temperature (80 to 400 K) measurements of the specular reflection coefficient using custom distributed-Bragg-reflector structures in the spectral range from 0.8 µm to 2.2 µm. All the compositions exhibited a nearly linear temperature dependence of n. For In_xGa_1-As, the temperature coefficient (dn/dT) increases from 2.0⋅10^-4K^-1 for x=0.06 to 4.5⋅10^-4K^-1 at x=0.25. In turn, the temperature coefficient of the In_xAl_1-As refractive index stays at the level of (1.7-2.0)⋅10^-4K^-1 at the considered indium contents.