Parametrization of optical properties of indium–tin–oxide thin films by spectroscopic ellipsometry: Substrate interfacial reactivity

M. LOSURDO; M. GIANGREGORIO; P. CAPEZZUTO; G. BRUNO; R. DE ROSA; F. ROCA; C. SUMMONTE; J. PLA; R. RIZZOLI

JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A - VACUUM SURFACES AND FILMS

American Institute of Physics

Año: 2002 vol. 20 p. 37 - 42

0734-2101

Indium–tin–oxide (ITO) films deposited by sputtering and e-gun evaporation on both transparent(Corning glass) and opaque (c-Si, c-Si/SiO2) substrates and in c-Si/a-Si:H/ITO heterostructureshave been analyzed by spectroscopic ellipsometry (SE) in the range 1.5–5.0 eV. Taking the SEadvantage of being applicable to absorbent substrate, ellipsometry is used to determine the spectra of the refractive index and extinction coefficient of the ITO films. The effect of the substrate surface on the ITO optical properties is focused and discussed. To this aim, a parametrized equation combining the Drude model, which considers the free-carrier response at the infrared end, and a double Lorentzian oscillator, which takes into account the interband transition contribution at the UV end, is used to model the ITO optical properties in the useful UV–visible range, whatever the substrate and deposition technique. Ellipsometric analysis is corroborated by sheet resistance measurements.