Influence of isochronal annealing on the evolution of hole traps in GaAsN epilayers grown by metalorganic chemical vapor deposition

The evolution of electrically active defects in rapid thermally annealed p-type GaAsN epitaxial layers grown by metalorganic chemical vapor deposition (MOCVD) was studied by deep level transient spectroscopy (DLTS). A continuous distribution of hole traps and an overlapping minority carrier trap are observed in the as-grown layers. Six hole traps HA1 (E_V+0.22 eV), HA2 (E_V+0.32 eV), HA3 (E_V+0.38 eV), HA4 (E_V+0.39 eV), HA5 (E_V+0.55 eV), and HA6 (E_V+0.78 eV) were created by rapid thermal annealing (RTA) in the temperature range of 600°C-900°C for 30 s. Most of these defects are stable at 900°C, although their relative concentrations varied over the RTA temperature. The origin of these hole traps was studied based on previously reported hole traps in the literature.