Abstract: The method is comprised of the following steps:implanting arsenic ions through a thin screen oxide layer in the regions of a P type silicon substrate where subcollectors are to be formed, at a dose less than 2.10.sup.16 at/cm.sup.2, partially etching said screen oxide layer to remove the upper portion, containing contaminating ions exposing to an oxygen ambiant to approximately reconstitute original thickness of the screen oxide layer and then annealing in an inert atmosphere, the substrate, to heal damages and distribute arsenic atoms in the substrate. It has been discovered that the step of reconstituting the original thickness of the screen oxide layer in an oxygen ambient, has the unexpected effect of permitting the subsequent growth of an absolutely defect free epitaxial layer.