Comment on “A model of hole trapping in SiO2 films on silicon” [J. Appl. Phys. 81, 6822 (1997)]

Recent measurements of oxygen-vacancy creation in Si/SiO2/Si structures during high temperature annealing which suggest an activation energy of 1.5 eV for the process have been interpreted in terms of a simple thermodynamic model. We demonstrate that this model is inconsistent with thermochemical calculations which indicate that the energy for this process is 4.5 eV [K. P. Huber and G. Hertz, Molecular Structure and Molecular Structure IV, Constants of Diatomic Molecules (Van Nostrand Reinhold, New York, 1979), p. 490]. Another process involving thermally induced oxygen out-diffusion at the SiO2/Si interface has an effective activation energy for oxygen-vacancy creation ∼2.0 eV, this is more consistent with the experimental data.