Polycrystalline high quality freestanding 300-&mgr;m-thick diamond films were doped by diffusion of B and Li under electric bias in order to fabricate verticalp-njunctions. Circular contacts were obtained by high dose ion implantation of B and Li. TheI–Vcharacteristics were rectifying. When illuminated by deuterium lamp, an open circuit voltage was 2.6 eV. The shape of theI–Vcharacteristic under illumination points to the existence of shunt and series resistances. The obtained structure is most probably ap-njunction with bad contacts. ©1997 American Institute of Physics.