Determination of random and aligned stopping powers for 80-300 keV protons in silicon by back-scattering measurements

The proton stopping powers random and aligned along the channels [110], [100], and [111] of silicon single crystals, in the energy range 80 to 300 keV, have been determined by measuring the energy of the protons back-scattered by a damaged layer previously produced by ion bombardment. The depth of this reference damage peak has been measured by using the technique introduced by Westmoreland et al (Proc. of the First Int. Conf. on Implantation, Thousand Oaks, May 1970 (Gordon and Breach, London, 1971)). Lindhard theory fits the random stopping powers till about 150 keV, whereas at energies of 100 keV and lower the data follow the trend of Brandt and Reinheimer theory (Phys. Rev.; B2:3104 (1970)). The ratio (α) between aligned and random stopping powers increases as the energy is lowered going from 0.68 to 0.83 for the channel [110], from 0.70 to 0.90 for the channel [100] and from 0.77 to 0.93 for the channel [111]. (author)