Systematics of the giant isotope effect in hydrogen ion blistering of materials

The giant isotope effect, observed when D ions were substituted for H ions in low energy blistering of silicon, challenged common assumptions based on ion irradiation theory and H-Si chemistry. We report a systematic investigation of the effect in several materials, in an attempt to identify its origin. Samples of Si, Ge, GaAs, 6H-SiC and SrTiO3 (STO) were implanted at 5 keV with various H or D doses (1 x (16) to 2 x 10(17) cm(-2)) and rapid thermal annealed. The resulting surface morphology was examined by atomic force microscopy. On Si and GaAs, D-ion blistering requires 2 to 3 times higher doses than H-ion blistering. On SiC, no D-ion blistering whatsoever is observed. On the other hand, on Ge and STO, there is little difference between H and D-induced blistering. For Si, Raman spectroscopy of Si-H/D bonding in conjunction with lattice kinetic Monte-Carlo calculations led to an interpretation of the effect in terms of reactions between the mobile entities, i.e. H (or D) atoms, vacancies and interstitials. The new data will be discussed by reference to this scenario. (c) 2007 Elsevier B.V. All rights reserved.