On the deactivation of the dopant and electronic structure in reactively sputtered transparent Al-doped ZnO thin films

• Published in: Journal of physics. D, Applied physics Vol. 43; no. 13; p. 132003
• Main Authors: Horwat, David, Jullien, Maud, Capon, Fabien, Pierson, Jean-François, Andersson, Joakim, Endrino, José Luis
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 07.04.2010; Institute of Physics
• Subjects: Aluminum; Azo; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Deactivation; Deposition by sputtering; Dopants; Electron states and collective excitations in thin films, multilayers, quantum wells, mesoscopic and nanoscale systems; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; Fysik; Heterogeneity; Ii-vi semiconductors; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; NATURAL SCIENCES; NATURVETENSKAP; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Physics; Resistivity; Thin films; Thin films and multilayers; Wurtzite; Zinc oxide; Electrical conductivity; XANES; Doping; Optical conductivity; Thin films; Energy gap; Electronic structure; Aluminium additions; Impurity site; Zinc oxide; Reactive sputtering; Absorption spectra; Microstructure; Physical Sciences
• ISSN: 0022-3727; 1361-6463; 1361-6463
• DOI: 10.1088/0022-3727/43/13/132003

We report on the possible origin of electrical heterogeneities in 4 at% Al-doped ZnO (AZO) reactively sputtered films. It is found through the Zn L3 and Al K edge x-ray absorption near-edge structure that a fraction of the Al dopant is deactivated by its positioning in octahedral conformation with oxygen. This fraction as well as the conductivity, optical bandgap and c-axis parameter of ZnO wurtzite are all found to depend on the sample position during deposition. The present results suggest the formation of a metastable Al2O3(ZnO)m homologous phase that degrades the electrical conductivity.