N-doped ZnO nanowires: Surface segregation, the effect of hydrogen passivation and applications in spintronics

• Published in: Physica status solidi. B. Basic research 2010-09, Vol.247 (9), p.2195-2201
• Main Authors: Xu, Hu, Rosa, A. L., Frauenheim, Th, Zhang, R. Q.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; defect levels; density-functional theory; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic structure of nanoscale materials : clusters, nanoparticles, nanotubes, and nanocrystals; Exact sciences and technology; II-VI semiconductors; Materials science; Nanoscale materials and structures: fabrication and characterization; Nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals; Physics; Quantum wires; spintronics; Structure of solids and liquids; crystallography
• ISSN: 0370-1972; 1521-3951
• DOI: 10.1002/pssb.201046059

We employ density‐functional theory (DFT) within the generalized‐gradient approximation (GGA) to investigate the formation energies, electronic structure, and magnetic properties of N impurities in zinc oxide (ZnO) nanowires. While the subsurface position is the preferential site for the N dopants in bare nanowires, upon hydrogen passivation N atoms segregate to surface sites. Additionally we show that the defect levels in these ultra‐thin wires are deeper than the ones in bulk ZnO, suggesting strong quantum dimensional effects. Finally we investigate the possibility of ferromagnetism induced by N in ZnO nanowires. Our spin‐polarized calculations show that, although N introduces a small net magnetic moment in ZnO, the interaction between N dopants is weak and strongly dependent on the N position.