Optimized energy window of He beams for accurate determination of depth in channeling Rutherford backscattering spectrometry

Abstract

We propose a method to improve accurate determination of damage/impurity depth profiles by channeling Rutherford backscattering by using He+4 beams in an energy window of 400–800 keV. This is based on the study of the stopping power of He+4 ions as a function of incident energy along the Si ⟨100⟩ axis, which shows that the channeling stopping power within the above energy window is close to the random stopping power. Experiments on 100 nm deep Sb-doped Si superlattices show that the approach significantly reduces the error in determining the depth location of Sb, for example, from 8% by using 2-MeV He+4 to 1% by using 600-keV He+4 ions.