Boron-doped polycrystalline diamond films of high quality were in situ grown on n-Si(100) in a hot-filament chemical vapor deposition chamber, using boric acid as the doping source. The current-voltage characteristic of the Al/p-polycrystalline diamond Schottky contact exhibits a peculiar hysteresis loop in either forward or reverse bias region. The area of hysteresis loop becomes larger when the applied bias voltage is scanned with a higher speed or at higher temperature. Hysteresis loop results from large capture and emission time constants which, respectively, characterize the time required for majority carriers to reach a steady-state value during charging and discharging processes. The large capture and emission time constants can be explained by the deep levels of high density and high activation energy in the boron-doped polycrystalline diamond film.