Comparison of the annealing characteristics of resistivity and vacancy defects for implant isolated n-type GaAs

Gallium arsenide layers, Si-doped at concentrations of 2x10(19), 1x10(19), and 5x10(18) cm(-3), grown on SI substrates were implanted using multiple-e nergy regimes, with O+, He+, and H+, respectively, to produce resistive str uctures. Sample resistivity was measured following annealing in the tempera ture range 400-800 degrees C. Maximum resistivity values were achieved afte r annealing at 600 degrees C for the O+ and He+ and 500 degrees C for the H + implanted sample. Equivalently implanted and annealed semi-insulating GaA s samples were analyzed using positron annihilation spectroscopy in the gam ma-ray Doppler-broadening mode, a technique which is predominantly sensitiv e to negatively charged, or neutral, vacancy-type defects. The annealing be havior of the resistivity is in good agreement with previous reports. Vacan cy defects to which the positron is sensitive are found to be removed from all semi-insulating samples at a temperature which is 100 degrees C below t hat at which maximum resistivity is achieved. Therefore, such vacancy types can be eliminated as the defect responsible for optimum electrical isolati on of GaAs following implantation, and the source of vacancies necessary to annihilate such defects. (C) 2000 American Institute of Physics. [S0021-89 79(00)03502-7].