Thermodynamic stability and optoelectronic property modulation of KTaO3 via substitutional doping with Sr, Ba, La and Pr

Abstract

Abstract In this work, we employ density functional theory (DFT) calculations to investigate the thermodynamics and optoelectronic properties of alkaline-earth (Sr and Ba) and rare-earth (La and Pr) metal dopants when introduced as substitutional defects in KTaO 3 . The structural, energetic and thermodynamic stability of the doped systems are examined with SCAN meta-GGA functional. On the other hand, the mBJ-LDA meta-GGA is employed for more accurate description of electronic and optical properties. Our results indicate that Sr, Ba and La dopants preferably substitute at the K-site of KTaO 3 . In contrast, Pr doping is thermodynamically more stable at the Ta-site of KTaO 3 . While Sr-, Ba- and La-doped systems exhibit electron-doped semiconductor behaviour, their threshold of optical absorption shift towards higher energy UV photons. On the contrary, doping of Pr at a Ta-site of KTaO 3 is found to be stable under oxygen-rich chemical environment and leads to a hole-doped semiconductor behaviour with optical absorption threshold shifted towards the visible region. Owing to growing interest in the properties emerging from doping of alkaline-earth and rare-earth elements in KTaO 3 in recent experiments, the outcomes of this study provide valuable insights into designing materials suitable for photocatalytic applications.