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DS: Fachverband Dünne Schichten

DS 15: Functional Oxides

DS 15.4: Talk

Tuesday, February 26, 2008, 16:00–16:15, H 2032

Effect of isothermal annealing on electrical and optical properties of Al-doped ZnO films — •Mykola Vinnichenko, Anatoly Rogozin, Natalia Shevchenko, Andreas Kolitsch, and Wolfhardt Möller — Institut für Ionenstrahlphysik und Materialforschung, Forchungszentrum Dresden-Rossendorf, P.F. 510119, 01314 Dresden, Germany

The aim of present work is to investigate mechanisms of Al incorporation and its effects on electrical and optical properties of ZnO films. Highly c-axis textured polycrystalline thin films of insulating ZnO were implanted by 110 keV Al⁺ ions and then annealed at 520 ^∘C. The films were characterized by Hall effect, four-point probe, spectroscopic ellipsometry and x-ray diffraction techniques. The films are nanocrystalline in as-implanted state. Their dielectric function shows broadened features near the band gap energy and increased, compared to unimplanted films, absorption in the near IR and visible spectral range. If the implantation dose is below 2x10¹⁶ cm⁻², the free electron density, Ne, increases after annealing and the film resistivity decreases monotonously during annealing. If the dose is above 2x10¹⁶ cm⁻², Ne decreases after annealing while film resistivity reaches minimum and then increases during the treatment. The annealing decreases optical absorption in the near IR and visible and improves film crystallinity. The behavior of the film electrical properties may be explained by the interplay between oxygen vacancies formation and Al donor activation.