Rapid thermal annealing effects on the optical properties of GaAs0.9−xNxSb0.1 structures grown by MBE

In this work, we report on the effect of rapid thermal annealing on GaAs0.9−xNxSb0.1 structures, grown by molecular beam epitaxy, using room temperature spectroscopic ellipsometry (SE). A comparative study was carried out on two sets of GaAs0.9−xNxSb0.1 as-grown and annealed samples with small nitrogen content (x up to 0.013). The results obtained from the ellipsometric data analysis allow us to extract the annealing effect on the pseudodielectric functions and the transition energies as function of nitrogen content. A blue shift of the E0 transition was recorded, while the higher E1, E1+Δ1 and E0′ transition energies are not affected with post-growth annealing. The nitrogen level EN, obtained from the band anticrossing model fit to the E0 transition energies values, is found to increase upon annealing from 1.60 (±0.06) eV to 1.80 (±0.08) eV. The resulting calculated electron effective mass is found to decrease with annealing the GaAs0.9−xNxSb0.1 structures.