Transient photocurrent experiments were performed to investigate trans
port and trapping kinetics in highly oriented (HOD) and polycrystallin
e (PD) chemical vapour deposition-diamond films perpendicular and para
llel to the growth direction. The results indicate better electronic p
roperties in PD then in HOD and do not reveal any transport anisotropy
in the HOD. Interactions with shallow bulk and grain boundary traps a
re detected in both PD and HOD. The main drift length is ca 1-2.6 mu m
. Deeply trapped carriers generate a space charge electric field which
was measured by d.c.-photoconductivity experiments in the short circu
it mode. The relaxation of the space charge field lasts for several mi
nutes at T=300 K, The decay is non-exponential and not thermally activ
ated in the regime 300-700 K. (C) 1998 Elsevier Science S.A.