Raman scattering studies of surface modification in 1.5 MeV Si-implanted silicon

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Abstract
The surface layer of crystalline siliconimplanted with 1.5 MeV Si ions with doses ranging from 1×1011 to 1×1015 Si+/cm2 has been studied by Raman scattering. Raman line intensities, shapes and shifts have been used to investigate the defects in the near‐surface layer. Above doses of 1×1013 Si+/cm2, Raman provides evidence for the presence of amorphous silicon islands within the crystalline structure. The phonon‐confinement model (PCM) which is based on the breakdown in wavevector selection rules due to scattering from finite domain sizes has been used to estimate the effective average distance between defects. The PCM has also been modified by introducing a term attributable to residual stress in the near‐surface layer. By fitting experimental Raman spectra with the modified PCM, the Raman line shifts due to stress effects are decoupled from those due to phonon confinement. The mechanisms for the stress creation are also discussed.