Ion implanted silicon detectors which are specially developed for timi
ng experiments show timing response variations of a few times 100 ps a
s a function of the position of irradiation. These variations are caus
ed by resistivity variations of a few times 10%. To quantify these res
istivity variations depletion depth studies have been performed for a
set of detectors. Best timing results are obtained with a high resisti
vity overdepleted detector.