AZIMUTHALLY AVERAGED BACKSCATTERING YIELD NEAR THE (100) AXIS IN SI

An azimuthally averaged backscattering yield near the [100] axis in Si is studied experimentally and by Monte Carlo simulation, for 1.5 MeV He-4 ions and tilt angles theta up to 16-degrees. A complete compensat ion of the (100) dip is obtained within 0-degrees less-than-or-equal-t o theta less-than-or-equal-to 6-degrees, in agreement with the rule of angular compensation. For larger tilts a fine structure in the yield, with a number of distinct secondary dips, is observed. The results of two simulation programs (CXX and FLUX) are found to be fully consiste nt with each other, and in excellent agreement with the experimental d ata. The extension of the simulation methods to include trajectories t hat substantially deviate from the string direction is presented.