On the peculiarities of silicon amorphization at ion bombardment

Pecularities of amorphous layer production in silicon under ion bombardment with middle energy ions were examined by electron diffraction. He4, B11, C12, N14, Ne20, P31, Ar40, As75, and Xe131 ion beams with energy of 50 keV were used. It was established that for light ions in a definite range of doses two amorphous layers are formed — an external layer and an internal one (sandwich structure). Doses necessary for amorphization and the thicknesses of the amorphous layers were determined. The results are discussed in terms of a model connected with the radiation defect accumulation. It is shown that for heavy ions the amorphization doses and the thicknesses of amorphous layers agree with the calculated distribution and concentration of radiation defects without taking account of their migration and annealing; for light ions under the given experimental conditions it is necessary to take account of the decreasing of a number of defects in the zone of displacements due to their migration and (or) annihilation. [Russian Text Ignored]