High-resolution X-ray diffraction was used to study the strain evolution of lattice defects formed in an array of B delta layers grown by molecular beam epitaxy and damaged by sub-amorphizing Ge self-implantation. The molecular beam epitaxial structure was implanted at room temperature with 840keV Ge to a dose of 1.5 x 1012/cm2. Firstly, a room-temperature strain reduction of ~40% was observed with respect to the strain value found in the just-implanted sample. This strain ageing phenomenon saturated after about 5 months. Then, the complete defects dissolution was monitored by in situ high-resolution X-ray diffraction during isochronal annealing. Three other strain-recovery steps were identified: the last at 157C. Moreover, secondary ion mass spectrometry performed after the strain recovery did not detect any B diffusion till the temperature was raised to 840C, measuring in this case a B diffusion equal to the equilibrium one.

Defects in Ge Caused by Sub-Amorphizing Self-Implantation - Formation and Dissolution. G.Bisognin, S.Vangelista, M.Mastromatteo, E.Napolitani, D.De Salvador, A.Carnera, M.Berti, E.Bruno, G.Scapellato, A.Terrasi: Thin Solid Films, 2010, 518[9], 2326-9