High Temperature Effects in Li-Doped ZnO Thin Films

Abstract

In this work, we present ellipsometric investigations of low-pressure plasma jet sputtered (Zn_0.5Li_0.5)O thin films at high temperatures. Optical measurements were performed with the J. A. Woollam spectral ellipsometer operating in rotating analyzer mode. High temperature measurements were performed with a specially designed heating system that allowed samples to be heated up to 520°C. The temperature dependences of surface roughness and the optical gap E_g were obtained for both cooling and heating directions. We didn't find any evidence of ferroelectric phase transition at ∼70°C described in [1] but we have observed band gap and surface roughness jumps at 300°C and 450°C that is a strong evidence of structural changes at these temperatures.

Keywords:

• Zinc oxide
• phase transition
• ellipsometry

ACKNOWLEDGEMENTS

This work was supported by 202/02/D078/A (Grant Agency of the Czech Republic) and the German Research Council (Deutsche Forschungsgemeinschaft) as a part of FOR520.