Structural change and its electrooptical effects on terahertz radiation with post-growth annealing of low-temperature-grown GaAs

This paper investigate how post-growth annealing of low-temperature grown GaAs (LT-GaAs) affects, the structural changes induced by the generation of point defects, as well as strain relaxation, the intensity and coarsening of As clusters with annealing, and the carrier recombination lifetime. The intensity and coarsening of As clusters is revealed by the analysis of bright field and high-resolution transmission electron microscopy (HR-TEM). The structural change is determined by the analysis of the intensity as well as a satellite reflection and a peak shift of the X-ray Bragg reflection. The investigation of the defect structures and the carrier lifetime change in the LT-GaAs are based on measurements of HR-TEM, X-ray, Hall, and terahertz spectrum. A systematic study of as-grown and post-growth annealed LT-GaAs reveals that the carrier lifetime is directly related to the intensity and distance of the As clusters. The electrical resistance of the LT-GaAs increases as the annealing temperature increases. A post-growth annealing condition was investigated for emitting and detecting terahertz signals and a photoconductive type dipole antenna was fabricated on the LT-GaAs.