Layers which were Si-doped to concentrations of 2 x 1019, 1019 or 5 x 1018/cm3, and grown on semi-insulating substrates, were implanted using multiple-energy regimes and O+, He+ and H+, respectively, to produce resistive structures. Equivalently implanted and annealed semi-insulating samples were analyzed by using positron annihilation spectroscopy in the γ-ray Doppler-broadening mode. The vacancy defects to which the positron technique was sensitive were found to be removed from all semi-insulating

samples at a temperature which was 100C below that at which maximum resistivity was attained. Therefore, such vacancy types could be eliminated as being the defects which were responsible for optimum electrical isolation following implantation, or the source of the vacancies which were necessary for the annihilation of such defects.

Comparison of the Annealing Characteristics of Resistivity and Vacancy Defects for Implant Isolated n-Type GaAs A.P.Knights, S.Ruffell, P.J.Simpson: Journal of Applied Physics, 2000, 87[2], 663-7