Oxidation and irreversible structural distortion of ScN at elevated temperatures

Abstract

We present optical and structural characterization of ScN exposed to high temperatures under air. Several sample pieces were heated up to 400–900 K while employing Raman spectroscopy for monitoring. After cooling back to room temperature, analysis by multiple characterization techniques, namely, Raman spectroscopy, spectroscopic ellipsometry, energy dispersive x-ray analysis (EDX), x-ray diffraction (XRD), and scanning-electron-microscopy (SEM) yields detailed insights into structural changes of ScN. Already at T=600K, irreversible changes are visible as witnessed, e.g., by Raman spectroscopy. Despite the observed changes of the ScN films’ properties, the crystal structure remains rock salt up to at least 700 K, which is further confirmed by SEM surface images and XRD. Oxidation and formation of oriented Sc2O3 grains as indicated by EDX, XRD, and SEM images occur between 800 and 900 K. Long time exposure to 900 K, finally, reveals a complete transformation of ScN to Sc2O3.