Temperature-dependent pseudodielectric functions of GaAs determined by spectroscopic ellipsometry

We present the pseudodielectric functions of GaAs in the temperature range between 30 and 650 °C. Data in the spectral range of 1.24<E<5.00 eV was obtained by spectroscopic ellipsometry in a molecular beam epitaxy system specially designed for this purpose. All measurements were performed in situ to avoid the presence of surface adsorbates, oxides, roughness and to ensure a group V stabilized surface is maintained. A simple two-phase model could thus be used to extract the dielectric functions. Temperature dependence of the critical point energies E1, E1+Δ1, E0′ and E2 are also determined.