Raman-based analysis of implantation-induced expansion and stresses in sapphire crystals

摘要

Raman spectroscopy was used to determine the lattice expansion and stress distribution within the ion implanted layer in sapphire crystals. The crystals with the (1120) face were implanted with 3.0 MeV H~+ ions to doses of 3.3 X 10~(17) cm~(-2) and 4.8 X 10~(17) cm~(-2). The strain components and their variation with depth were analyzed by measuring the shift of the Raman peak on the cross-sectional basal plane. A continuum mechanics approach considered a model of a semi-infinite anisotropic elastic space subjected to the implantation-induced lattice expansion. The expansion and resulting compressive stresses were found to increase with depth, reaching a sharp maximum at the end of the ion range. The implantation-induced expansion coefficient was shown to be independent of the ion energy loss and implantation depth in sapphire. Such behavior was discussed in light of stopping and range of ions in matter data and defect production by nuclear collisions and ionization processes.