We have investigated the structure and the electronic properties of thin SiC films grown on Si(100) by plasma-assisted chemical vapor deposition from CH4 diluted in H-2 It was found that the growth proceeds through the nucleation of cubic and relaxed crystalline SIC islands preferentially oriented in the (100) direction. The average-island size increases with carbonization time up to a maximum size consisting of similar to 300 nm lateral width and similar to 100 nm height. We were able to determine the valence band discontinuity although the SIC overlayers were clusterlike End did not cover uniformly the Si substrate. The found value is 0.77+/-0.08eV.