Tracks induced by swift heavy ions in semiconductors

InSb, GaSb, InP, InAs, and GaAs single crystals were irradiated with Pb ions in the range of 385--2170 MeV. The samples were studied by transmission and high-resolution electron microscopy and Rutherford backscattering in channeling geometry. The energetic ions induced isolated tracks in all crystals but GaAs. The thermal spike analysis revealed that the variation of the damage cross section with the ion energy is considerably weaker than in insulators. The widths of the thermal spike $a(0)$ was estimated. The analysis was extended to recent C₆₀ experiments on Ge and Si. A quantitative relation was found between $a(0)$ and the gap energy Eg: $a(0)$ is reduced with increasing Eg, and its lowest value is close to that found in insulators.