INDUCED DAMAGE BY HIGH-ENERGY HEAVY-ION IRRADIATION AT THE GANIL ACCELERATOR IN SEMICONDUCTOR-MATERIALS

The advantages of using a high energy (several GeV) heavy ion accelerator for irradiation are first recalled: the ranges of ions in materials are significant; an a priori relative evaluation of the damage creation rates from elastic collisions is possible: last, the ratio of the electronic stopping power to the nuclear stopping power is very large. The experimental methods used are in situ resistance and Hall mobility measurements. The irradiated samples are also analyzed in the laboratory by means of different methods (DLTS. photoluminescence, electron microscopy). electron microscopy). The resistance has the same behaviour in silicon and gallium arsenide. It increases continuously during the irradiation. On the other hand, in n-type germanium, the resistance first increases, passes through a maximum, and decreases afterwards. A type-conversion takes place in the material. Moreover. the comparison of damage creation rates from one irradiation to another, in germanium and gallium arsenide. seems to show that the electron excitation produces a relative decrease of the damage creation rate. This effect is not visible in silicon.