An investigation was made of the annealing-temperature dependence of the properties of heavily As-implanted material. The amount of excess As was similar to that in low-temperature GaAs. It was found that the fundamental properties of the present material were quite similar to those of low-temperature GaAs. High-resolution X-ray diffraction measurements revealed that the present material had an increased lattice constant. This was reduced to the bulk value by annealing at temperatures of between 300 and 400C. Electrical conduction in this material was dominated by hopping between deep states, and was also reduced upon annealing at temperatures above 350C. In samples which were annealed at temperatures ranging from 600 to 850C, the predominant electron trap was EL2. It was confirmed, by resistivity measurements of n-i-n structures, that the Fermi level was pinned by EL2. In samples which were annealed at temperatures below 500C, the predominant electron trap was not EL2, but the U-band. However, electron paramagnetic resonance measurements revealed the existence of a large concentration of the ionized As antisite defect, AsGa+. This supported the suggestion that the U-band was formed from AsGa+ defects with slightly modified carrier emission properties, as compared with EL2.

H.Fujioka, J.Krueger, A.Prasad, X.Liu, E.R.Weber, A.K.Verma: Journal of Applied Physics, 1995, 78[3], 1470-5