Diamond films (DF) were prepared on P-type (10 0) oriented Si substrates by hot filament chemical vapor deposition (HFCVD). In order to study the lattice damage produced by ion beam doping, the films were implanted with 160 keV He+ to fluences of 5 x 10(14) to 3 x 10(16) cm(-2), respectively. Scanning electron microscopy (SEM) and Raman spectra reflected that the DF were sequentially damaged versus radiation fluence. When the radiation fluence was smaller, the lattice damages could be partially removed by post-annealing. Increasing the radiation fluence, the DF grains decrease in size and become vague in boundaries. In addition, electrical measurements were also carried out. Post-annealing stimulated the transformation of SP3 bonded configuration to amorphous and/or micro-polycrystal line graphite. (C) 2004 Elsevier B.V. All rights reserved.