Dresden 2006 – wissenschaftliches Programm
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DS: Dünne Schichten
DS 1: Optical properties of thin films I
DS 1.1: Vortrag
Montag, 27. März 2006, 09:30–09:45, GER 37
Spectroscopic ellipsometry of ZnO thin films grown by pulsed reactive magnetron sputtering at elevated temperatures — •M. Vinnichenko1,2, A. Rogozin1, N. Shevchenko1, M. Ozerov2, A. Kolitsch1, and W. Möller1 — 1Institut für Ionenstrahlphysik und Materialforschung, Forchungszentrum Rossendorf, P.F. 510119, 01314 Dresden, Germany — 2Division of Optics, Department of Physics, National Kyiv Taras Shevchenko University, 01033 Kyiv, Ukraine
Understanding of the growth process of undoped ZnO thin films is important for optoelectronic applications of the material. In this study, ZnO layers were deposited at single crystalline Al2O3 (0001) substrates by pulsed reactive magnetron sputtering. Oxygen partial pressure, base pressure and the substrate temperature (Ts) were varied systematically. The films were characterized by spectroscopic ellipsometry (SE), Seebeck effect measurements and X-ray diffraction (XRD). SE data were analyzed by using graded layer model for the film with Lorentz oscillator parameterization of the ZnO optical constants. The films produced at low temperatures always have negative Seebeck voltage, while at Ts>540 ∘C it changes to low positive values, which, however, degrade to negative values within several hours. The Lorentz oscillator broadening for the films grown at these temperatures increases with oxygen flow which points to a formation of more disordered structure inside ZnO grains in this case. XRD analysis yields decreasing grain size and increasing rocking curve full width on a half maximum with oxygen flow enhancement at the same Ts.