The authors prepared nanodiamond-cluster-embedded diamondlike carbon (DLC) composite films by electrophoresis deposition followed by magnetic filtered cathodic vacuum arc plasma deposition. Nanodiamond clusters are uniformly embedded into the DLC films. The authors investigated the location of the emission sites with nanometer scale accuracy and the emission mechanism using scanning probe microcopy (SPM) based technique. These composite films show better field emission properties than the as-deposited DLC film and as-deposited nanodiamond clusters. It is revealed that electrons are emitted primarily from the nonconducting boundaries surrounding the embedded nanodiamond cluster. Thus, by depositing nanodiamond clusters, an emission site may be predetermined; this is very useful in fabricating nanoelectron sources. (c) 2008 American Vacuum Society.