High-temperature thermal stability of nanocrystalline Cr2O3 films deposited on silicon wafers by arc ion plating

In this work, the high-temperature thermal stability of nanocrystalline Cr2O3 films on Si wafers deposited at various bias voltages was systematically investigated by means of a symmetrical high-resolution thermogravimetric system. In the meantime, the effects of substrate bias voltage on the morphology, microstructure, crack area percentage, phase constituents, and grain size of the heat-treated Cr2O3 films were also studied in detail. The results showed that the Cr2O3 films presented the higher thermal stability in pure nitrogen than in air up to 1200 °C because the brittle oxidation product was more prone to cracking and chipping. As the bias voltage was − 100 V, the Cr2O3 film showed the highest thermal stability which was attributed to its most compact structure and the lowest defect density. After the heat treatments, all the films cracked due to the big difference in thermal expansion coefficient between the Cr2O3 film and Si wafer, which caused large thermal stresses. And some obvious micro-cavities were left in the film cross section after oxidation owing to the vaporization of Cr2O3 in oxygen containing atmosphere. In addition, the heat treatment also had a strong influence on the grain size of the Cr2O3 films.