Samples of n-type crystalline silicon were exposed to different fluenc
es, ranging from 1.25 to 5X10(14) ions/cm(2), of 90 MeV silicon ions.
The induced disorder in the surface region was studied by grazing-angl
e x-ray-diffraction and optical reflection spectroscopy, and that in t
he bulk was studied by measuring the lifetime of the excess minority c
arriers generated by a 1 MeV pulsed electron beam. Both in the surface
region, as well as in the bulk, the degree of induced lattice defects
was found to increase with an increase in the ion fluence. The value
of the damage coefficient, estimated from the lifetime of the minority
carriers, gradually increased from 1.2X10(-10) to 8.9X10(-10) cm(2) s
(-1) over the range of ion fluences. These results indicate that 90 Me
V silicon ions create an appreciable number of defects in crystalline
silicon, the concentration of which increases from the surface to thei
r projected range of similar to 31 mu m, and at higher fluences second
ary defects are also produced in the bulk. Even at the highest fluence
used the energy deposited through electronic loss had no observable e
ffect on annealing the induced defects. (C) 1995 American Institute of
Physics.