Nanostructured diamond films are deposited on mirror-polished silicon wafers under continuous ion bombardment by using a hot-filament chemical vapor deposition (HFCVD) chamber equipped with a substrate bias system. The morphology and phase purity of the diamond film, as related to the different deposition parameters, are evaluated by scanning electron microscopy (SEM) and Raman scattering spectroscopy. The results show that nanostructured diamond films with a large area, low stress and smooth surface can be synthesized on mirror-polished Si substrates by an economical HFCVD method, and the size of diamond clusters in the film can be controlled by a suitable selection of deposition parameters such as the bias current density and the ratio of CH4 to H-2. Furthermore, the relationship between the film's stress and the diamond clusters' size for the films synthesized under various parameters is revealed. The measurement of field emission from an as-grown nanostructured diamond film shows properties of a low emission threshold and a stable high-emission current density. (C) 2004 Elsevier B.V. All rights reserved.