Surface Reconstruction, Oxidation Mechanism, and Stability of Cd3As2. (29th April 2019)

• Record Type: Journal Article
• Authors: Gao, Junfeng; Cupolillo, Anna; Nappini, Silvia; Bondino, Federica; Edla, Raju; Fabio, Vito; Sankar, Raman; Zhang, Yong‐Wei; Chiarello, Gennaro; Politano, Antonio
• Is Part Of: Advanced functional materials. Volume 29:Number 26(2019)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2019-04-29
• Subjects: density functional theory, Dirac semimetals -- high‐resolution electron energy loss spectroscopy -- surface science -- X‐ray photoelectron spectroscopy; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.201900965
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: Cadmium arsenide (Cd3 As2 ) has recently attracted considerable interest for the presence of 3D massless Dirac fermions with ultrahigh mobility and magnetoresistance. However, its surface properties are currently largely unexplored both theoretically and experimentally, due to the very large unit cell and the challenging growth of single‐crystal samples, respectively. Here, by combining ab initio calculations with surface‐science spectroscopic experiments, the presence of a surface reconstruction is unveiled in centimeter‐scale (112)‐oriented Cd3 As2 single‐crystal foils produced by the self‐selecting vapor growth. Outermost Cd atoms descend into the As‐sublayer with a subsequent self‐passivation of the dangling bonds with As atoms, forming the triangle lattice previously imaged by scanning tunneling microscopy. Moreover, the oxidation mechanism of this reconstructed surface, dominated by the formation of AsOCd bonds, is revealed. Interestingly, it is found that the band structure of the reconstructed surface of Cd3 As2 is quite robust against surface oxidation. Both computational and experimental findings point to a successful exploitation in technology of Cd3 As2 single crystals. Abstract : The (112) surface of Cd3 As2 reconstructs with Cd atoms descending into the As‐sublayer with a subsequent self‐passivation of the dangling bonds with As atoms . The oxidation mechanism is dominated by the formation of AsOCd bonds. The sticking coefficient for oxygen is <10 −3 at room temperature, although encapsulation is necessary for devices.