Layers of δ-doped B, as grown by molecular beam epitaxy and characterized by secondary ion mass spectrometry, were used to investigate the migration of Si self-interstitials during irradiation with MeV protons at 500 to 850C. Following growth, the samples were thinned (from the reverse side) to a thickness that made them transparent to the proton energies which were used. As a result, the generation rate of point defects could be considered to be essentially uniform throughout the sample. However, the evolution of B profiles was almost identical to that observed following the injection of self-interstitials; as caused by the thermal oxidation of samples at high temperatures. This strongly suggested that the surface acted as a reflective boundary for migrating self-interstitials or/and as an efficient sink for mobile vacancies. Higher values of interstitial supersaturation in the near-surface region, in proton-bombarded samples, was consistent with the experimentally detected depth-dependence of the immobile fraction in B clusters.

Self-Interstitial Migration during Ion Irradiation of Boron Delta-Doped Silicon. A.Y.Kuznetsov, P.Leveque, A.Hallen, B.G.Svensson, A.N.Larsen: Materials Science in Semiconductor Processing, 2000, 3[4], 279-83