Concordant element of the oxidation kinetics—Interpretation of ellipsometric measurements on Zr

Abstract In this study we report on the growth of ZrO 2 films upon the gradual thermal annealing of Zr in the temperature range of 500–700 K. The thickness of the oxide was monitored by in-situ spectroscopic ellipsometry with temporal and thickness resolutions of a few seconds and a few nanometers, respectively. A remarkable feature of the process was that the growth of the oxide can be terminated immediately when decreasing the temperature by a few K. This suggests that, in addition to the driving force, a built-in control adjusts the final thickness determined only by the temperature in sync with the formation and growth of dense oxide films. The derived phenomenological model includes the concept of a ‘depletion layer’ known from semiconductor physics. The validity of the model and the pressure dependence of oxidation is discussed.