Deep-level transient spectroscopy was used to investigate the effect of post-growth annealing upon the concentration of deep defects in Cl-doped epilayers. The samples were grown, by means of molecular beam epitaxy, onto (100)GaAs substrates. The Cl-doped epilayers were annealed in Zn-rich atmospheres at temperatures ranging from 400 to 650C, for 18 to 60h. Due to the heat treatment, the total concentration of deep defects in the material was significantly reduced. In particular, annealing almost completely eliminated the main defects which were present in as-grown material. These were located at 0.51eV below the edge of the conduction band. This strongly supported the suggestion that these defects were Zn-vacancy complexes. It was also noted that annealing introduced a small concentration of new defects. The activation energies for electron emission and capture of these traps were 0.24 and 0.17eV, respectively; thus indicating that this level lay at 0.07eV below the conduction band.

B.Hu, G.Karczewski, H.Luo, U.Bindley, J.K.Furdyna: Journal of Applied Physics, 1995, 77[5], 2026-8