Effect of rapid thermal annealing on the optical properties of MBE growth GaNAs films

摘要

We report the effect of rapid thermal annealing (RTA) on the optical properties of GaN_(0.01)As_(0.99) samples grown by molecular beam epitaxy. In particular, a blueshift of the PL peak energy is observed when annealing the samples at 650—900℃. Samples annealed showed pronounced enhancement in PL intensity as compared to the as-grown sample, and 850℃ is proposed as the optimum RTA temperature. The results are examined as a consequence of RTA-induced nitrogen diffusion inside the GaN_(0.01)As_(0.99) material rather than diffusion out of the alloy, which homogenizes initial nitrogen composition fluctuations. In addition, for photo-modulated reflectance (PR) spectra of RTA samples, the fundamental band gap transition (E_0) and the transition from the spin-orbit split-off valence band (E_0 + Δ_0) are observed. Both of the two transitions increase with increasing annealing temperature.