many studies of oxidation kinetics, it has been observed that SiO2 growth in dry oxygen in the thin regime (<500Å) is faster than the classic description of growth in thicker layers by a linear-parabolic relationship. Growth-rate enhancement in the thin regime was studied in the 800°-1000°C range under a variety of substrate doping densities and 02 partial pressures using in situ ellipsometry. The enhancement in oxidation rate is found to decay exponentially with thickness, and its thickness extent is approximately independent of substrate orientation, doping density, and oxygen partial pressure; its oxygen pressure and substrate doping dependence suggest that it is caused by physical mechanisms associated with the substrate. Such mechanisms are discussed in part II of this paper (11). © 1985, The Electrochemical Society, Inc. All rights reserved.