Abstract
Oxidation studies of CVD 
were performed in dry oxygen, oxygen‐argon, and oxygen‐nitrogen‐argon gas mixtures of various oxygen and nitrogen partial pressures at a total pressure of 1 atm at 1100°–1400°C. Parallel oxidation studies of single‐crystal silicon were also conducted for direct comparison. It was observed that the oxidation of both 
and Si followed parabolic growth kinetics with activation energies of about 115 kcal/mol and about 30 kcal/mol, respectively. The formation of a single layer of 
and evolution of 
could not account for the much lower parabolic rate constants and much higher activation energy for 
than for Si during the oxidation. Detailed characterization of the oxidation scales using ellipsometry, step‐by‐step etching, SIMS, and XPS techniques indicated that a duplex oxidation scale consisting of 
and 
was formed when 
was oxidized. The intermediate 
scale was identified as a single‐phase material, not a physical mixture of 
and 
. The low oxidation rate and high activation energy for 
during the oxidation were attributed to the formation of 
and low oxygen diffusivity in this structurally dense phase.