We determined the annealing dynamics of AsGa antisite defects in As ion-implanted GaAs based on a model where AsGa antisite defects trap photo-excited carriers. An Arrhenius plot of the carrier decay rate vs. annealing temperature in the high temperature regime gave an energy EPA, which was different from true activation energy. The annealing time dependence of EPA obtained by the two diffusion models (self diffusion and VGa vacancy assisted diffusion of defects) were compared with EPA's obtained form already published works, which proved that the density of VGa vacancy was high enough to assist the diffusion of AsGa antisite defects and that the annealing dynamics of AsGa antisite defects was VGa vacancy assisted diffusion.
Terahertz electromagnetic pulse generation using photoconductive emitters, their characterization, real-time imaging, and spectroscopies using them are described. Intense THz pulses were generated using a large-aperture photoconductive antenna. Real-time imaging were performed for the pulse characterization and acquisition of 1-kHz high-speed movies of moving objects. Tunable THz pulse generation and ultrafast semiconductor spectroscopy using photoconductive antennas will also be described.