A correlation between the partial pressure of dichlorosilane gas (SiH2Cl2) and the incorporation of oxygen (O) and chlorine (Cl) atoms into the low‐temperature (850 °C) epitaxial films was found. The profiles of O and Cl concentrations in the epitaxial films were measured by secondary ion mass spectroscopy. Incorporation of O and Cl atoms into the growth films during the epitaxial growth was suppressed by increasing the partial pressure of SiH2Cl2. The growth rate linearly increased with the partial pressure of SiH2Cl2and eventually saturated. Incorporation of O atoms was inhibited and fine removal of Cl atoms was achieved when the growth rates saturated. The epitaxial films with high O and Cl concentrations had a microroughened surface (root mean square of microroughness ≳0.4 nm). The microroughness was also improved by increasing the partial pressure of SiH2Cl2. The coverage of kinks and/or hollow bridge sites by hydrogen (H) and Cl atoms seems to restrict the reaction of O and water (H2O) with the growth front surface. ©1995 American Institute of Physics.