Ripple morphology versus Ar+ implantation dose in silicon

Investigations of ripples morphology of Ar+ implanted silicon are presented. Particularly we have measured the degree of amorphization as a function of implantation dose by means of x-ray grazing amorphous scattering (GIAS). For perfect silicon crystals GIAS shows monotone decreasing background intensity versus the 2theta scattering angle. For implanted samples we find two broad peaks indicating short-range ordering of amorphous material changing with the penetration depth of probing x-ray. The appearance of embedded crystalline domains is indicated by additional sharp peaks on top of the amorphous scattering. 2theta- scans taken at different azimuthal angles of sample display strong anisotropy of amorphous scattering which only slightly changes with dose. Based on these results we suggest a model of dose-dependent amorphization. The strong damage of crystalline structure takes place along particular crystallographic directions and strongly reveal for low doses, before it becomes complete amorphous and mostly uniform at high doses of implantation. This mechanism can be used as a hint for the appearance of a ripples amorphous-crystalline interface found at these structures.

We would like to thank S. Hazra and T.K. Chini for research collaborations.
This work was supported by the DST-DAAD India-Germany