Back-scattering of Fast Protons from Silicon Single Crystals

Abstract

The <111> axial and (110) planar channeling of 200 keV protons in silicon have been studied by measuring the yield of back-scattering (scattering angle : 135°). The results are in good agreement with the theory of Lindhard and Erginsoy. The observed critical angles and the minimum scattering yield agree with the theoretical values with decreasing depth below the crystal surface. The analysis of the energy spectra of backscattered protons indicates that the axial and planar channeling probabilities of the protons at the clean surface are 0.93 and 0.66, respectively, and that the shoulder parts of the yield curves are mainly due to back-scattering from the surface layer of the crystal rather than to some imperfections of its surface.