We report the growth of continuous diamond thin films by bias-assisted hot filament chemical vapor deposition onto hexagonal boron nitride films prepared by plasma chemical vapor deposition on silicon substrates. Negative substrate biasing during the early stages of diamond growth greatly increased the nucleation density. Values of1010 cm−2were achieved at −250 V for bias times as short as 25 min. After the nucleation stage, high quality polycrystalline continuous diamond films, as revealed by scanning electron microscopy and Raman analysis, were grown under standard hot filament deposition conditions. ©1997 American Institute of Physics.