Cr2O3 layers deposited on sapphire substrates by mist-CVD and RF magnetron sputtering

We have developed corundum-like Cr₂O₃ / α-Al₂O₃ heterostructures using a novel mist-CVD technique, varying the growth parameters to modify the morphology and crystallinity of the Cr₂O₃ films. This technique is considered as an alternative to conventional radio-frequency (RF) magnetron sputtering, which requires a subsequent annealing due to low crystal perfection of the sputtered films. Layers deposited by both techniques are analyzed. The highest crystallinity among magnetron sputtered films was achieved in case of 3-hour annealing at 350 °C, however, any of the films grown by mist-CVD possess the mosaic spread with less-misoriented blocks. Moreover, the mist-CVD films own a much more developed morphology with a substructure of specifically oriented crystallites, that can be modified directly during a growth process. It has been shown that the growth rates of Cr₂O₃ films by chemical vapor deposition are significantly higher than in the case of sputtering. Thereby, Cr₂O₃ / α-Al₂O₃ heterostructures grown by mist-CVD technique may have applications as functional semiconductor surfaces.