Influence of post-deposition annealing on the properties of transparent conductive nanocrystalline ZAO thin films prepared by RF magnetron sputtering with highly conductive ceramic target

• Published in: Thin solid films Vol. 418; no. 2; pp. 156 - 162
• Main Authors: Fang, Guojia J, Li, Dejie, Yao, Bao-Lun
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15.10.2002; Elsevier Science
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Deposition by sputtering; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport phenomena in thin films and low-dimensional structures; Exact sciences and technology; Low-field transport and mobility; piezoresistance; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Nanoscale materials and structures: fabrication and characterization; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Other nonmetallic inorganics; Other nonmetals; Physical properties; Physics; RF magnetron sputtering; Structural characterization; Vacuum annealing; Visible and ultraviolet spectra; ZAO transparent and conductive thin films; RF magnetron sputtering; Vacuum annealing; ZAO transparent and conductive thin films; Physical properties; Structural characterization; Inorganic compounds; Electrical conductivity; Crystal chemistry; Crystal growth from vapors; Nanostructures; Characterization; Thin films; Optical transmission; Optical properties; Carrier mobility; Thermal annealing; Nanocrystal; Radiofrequency sputtering; Semiconductor materials; Electrical properties; Transition element compounds; Doped materials; Experimental study; Magnetrons; Zinc oxides; Aluminium additions; Ultraviolet visible spectrum; Carrier density
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/S0040-6090(02)00733-2

Using a highly conductive ZnO (ZnAl 2O 4) ceramic target, c axis-oriented and oxygen-deficient Al-doped ZnO (ZAO) thin films were prepared on glass sheet substrates by radio frequency (RF) planar magnetron sputtering. The structural, electrical and optical properties of the films (deposited at room temperature and annealed at different conditions) were characterized with various techniques. The experimental results show that the electrical resistivity of as-grown films can be decreased to 10 −4 Ω cm level with post-deposition annealing at 400 °C for 2 h in a vacuum pressure of 10 −5 torr. By increasing the annealing temperature, the oxygen vacancies and carrier concentration of ZAO thin film increase, and the absorption edge in the transmission spectra shifts toward the shorter wavelength side (blue shift). The oxygen vacancy plays an important role in the electrical conductivity. The more the oxygen vacancies exist in ZAO thin films, the higher the electrical conductivity will be.