Ion-beam channeling in a single-surface modified Si membrane

Abstract

The scattering and energy distributions of ions (²²Ne⁺ and ⁴He⁺) transmitted through a Ga implanted single-crystal Si (0 0 1 ) membrane are studied both experimentally and with a Monte-Carlo binary collision approximation code (IMSIL). The membrane is studied in both a [0 0 1] orientation to the ion beam as well as an inverted orientation. Both the scattering and energy distributions of the transmitted particles reveal a strong dependence on the membrane orientation due to the amorphization of the Si surface. When ions well-aligned to the [0 0 1] axis first encounter the crystalline layer, they primarily travel along the axial channel before being randomly scattered by the amorphous surface layer, yielding a random scattering distribution. Alternatively, when the trajectories are initially randomized by the amorphous surface, a large fraction of the ions are directed to higher energy-loss pathways upon entering the crystal, such as planar channels and random trajectories. The resulting scattering distribution reveals the crystalline features of the sample (e.g., star pattern) but with a larger energy spread and a higher average energy loss than the former case. This work aims to extend transmitted ion beam imaging and ion energy-loss analysis in the keV range to complex heterostructures with both crystalline and amorphous regions.