Enhancing thermoelectric properties of ScN films through twin domains

Abstract

Tailoring thermoelectric properties of ScN-based materials is of vital importance for their application, particularly at high operating temperatures. Here, we report on the thermoelectric properties of the ScN layers deposited on MgO (001) substrates by the DC reactive magnetron sputtering. The microstructure of the produced thin films is examined by X-ray diffraction and atomic force microscopy, while their chemical composition and contamination by defects are determined by X-ray photoelectron spectroscopy. The effect of temperature on the phonon properties of ScN layers, having implications for their thermoelectric properties, is explored by Raman spectroscopy. The results of our experiments are confronted with those following from the first-principles studies. We find that the ScN/MgO(001) layers with twin-domain structure reveal enhanced thermoelectric properties at elevated temperature as compared to those measured for almost defect- and domain-free layers, namely, enlarged Seebeck coefficient by about 30% and over two and a half times increased figure of merit at 800 K. Therefore, structural twin domains in thin ScN film appear to be a simple and rather stable solution for the improvement of its thermoelectric properties at elevated temperatures.