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A depth-resolved Raman spectroscopy technique was used to study the residual stress profiles in polycrystalline silicon nitride that was irradiated with Xe (167 MeV, 1 × 1011 cm−2 ÷ 4.87 × 1013 cm−2) and Bi (710 MeV, 1 × 1011 cm−2 ÷ 1 × 1013 cm−2) ions. It was shown that both the compressive and tensile stress fields were formed in the irradiated specimen, separated by a buffer zone that was located at a depth that coincided with the thickness of layer, amorphized due to multiple overlapping track regions. The compressive stresses were registered in a subsurface region, while at a greater depth, the tensile stresses were recorded and their levels reached the maximum value at the end of ion range. The size of the amorphous layer was evaluated from the dose dependence of the full width at half maximum (FWHM) (FWHM of the dominant 204 cm−1 line in the Raman spectra and scanning electron microscopy.

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A multiscale modeling is applied to investigate structural changes caused by impacts of swift heavy ions in Si3N4 nanoclusters imbedded into amorphous and crystalline silicon nitride matrices. The approach combines the Monte Carlo code TREKIS describing the excitation kinetics of electronic and atomic subsystems and a classical molecular dynamics tracing subsequent relaxation of lattice atoms. Ion impacts in amorphous and crystalline Si3N4 result in formation of a cylindrical amorphous region of a reduced material density, surrounded by a shell with an increased density. The track diameter inside a nanosized inclusion in crystalline or amorphous matrices was found smaller than in surrounding materials, which can be explained by a heat confinement by grain boundaries.

Depth-resolved Raman piezospectroscopy was used to study residual mechanical stress profiles in polycrystalline silicon and aluminum nitrides irradiated with 710 MeV bismuth ions to fluences of 1×10 12 , 2×10 12 , and 1×10 13 cm -2 . It was found that stress fields of opposite signs are formed in the irradiated Si3N4 layer, separated by a buffer zone located at a depth coinciding with the thickness of the sample layer, amorphized at high ion fluences due to multiple overlapping of track regions. At great depths, tensile stresses witch magnitude reaches their maximum value in the region of the end of the ion range are detected. In contrast to Si3N4, radiation-stimulated changes in mechanical stresses in AlN were within the measurement error throughout the entire thickness of the irradiated layer, except of the near-surface region. The observed effect is associated with the different structural sensitivity of silicon and aluminum nitrides to high-density ionization -the formation of amorphous latent tracks in Si3N4 and their absence in AlN.