The effects on minority carrier diffusion length and surface recombination velocity of the oxidation of p‐type silicon in a copper contaminated ambient have been analyzed using electron beam induced current. The experiments were carried out on Czochralski and float‐zone silicon in order to obtain two different microstructures of defects and copper precipitation modes at the interface, and to study the influence, respectively, on the diffusion length and surface recombination velocity. The diffusion length was drastically decreased in regions free of extended defects, showing the existence of pointlike recombinant defects in the matrix. In each case, it has been evidenced by electron beam induced current measurements and imaging that these pointlike defects were passivated by hydrogen radio‐frequency plasma annealing, while no effect was observed on extended recombinant defects. © 1995 American Institute of Physics.