Measurements of the ratio between planar and random stopping power for 80 to 300 keV protons in silicon

High resolution backscattering measurements are performed in the (110)-plane of silicon single crystals with 80 to 300 keV protons. The observed oscillatory spectra are in good agreement with analytical calculations. The first two maxima of the spectra are used for the determination of the ratio between planar and random stopping power γ for quasi-channelled protons. This ratio turns out to be energy-dependent and larger than unity. The half-wavelengths λ/2 of the oscillations are calculated on the basis of the Fokker-Planck equation. Conclusions for the ion–atom potential are deduced.