In order to produce a highly oriented diamond layer on a silicon (100) substrate, reaction conditions should be controlled so as to achieve an initial selective growth on the (111) face, followed by the (100) face. In the present study, cubo-octahedral diamond crystals were formed by the microwave plasma-assisted chemical vapor deposition of methane and hydrogen on a silicon (100) wafer. Trimethylboron and dimethylsulfur as the boron or sulfur sources, respectively, were added to the gas phase and diamond was homoepitaxially deposited on the {100} and {111} of the crystals. The growth rate determined from geometrical changes in the crystals, was affected by the type of diamond faces used, the boron to carbon (B/C) and sulfur to carbon (S/C) ratios in the gas phase, the methane concentration, and the substrate temperature. The growth rate decreased with increasing B/C and S/C ratios, but the relative growth rate of [100] to [111] remained nearly independent of the dopant concentration. The [111] preferred growth was realized under lower methane concentrations and higher substrate temperatures.