Vibrational signatures of hydrogen defects in delafossite CuMO2 (M=Al, Ga, In): Hybrid density-functional calculations

Hydrogen impurities are known to significantly influence the electronic properties of delafossite oxides CuMO2 (M = Al, Ga, In) by passivating acceptor defects, thereby impacting the p-type conductivity of these materials. Identifying H and its configurations is therefore important to understand the properties of these materials. In this study, we employ hybrid density-functional theory calculations to investigate the vibrational properties of various hydrogen-related defects, including interstitial hydrogen (Hi), the hydrogen-copper antisite complex (Hi-CuM), and hydrogen-copper vacancy complexes (Hi-VCu, 2Hi-VCu). Our calculations provide the first theoretical predictions of local vibrational modes (LVMs) associated with these defects, revealing frequencies ranging from approximately 2,800 cm−1 to 3,800 cm−1. These results offer valuable insights into the behavior of hydrogen in CuMO2 and serve as a reference for future experimental investigations using techniques such as infrared (IR) spectroscopy. By identifying distinct vibrational signatures for different hydrogen configurations, this study lays the groundwork for defect characterization and passivation mechanisms in delafossite oxides, which are critical for optimizing their electronic and optical properties.