Current trends for developing novel functional metal oxides
Mircea Modreanu
Tyndall National Institute, University College Cork, Lee Maltings Dyke Parade, Cork, Ireland;

Functional metal oxides have a wide variety of technological applications attracting a large interest over the past decade.  One particular class of functional metal oxides is represented by transparent conductive oxides (TCOs) that are cornerstone for the development of an emerging area, the transparent electronics. TCOs are an unusual class of materials possessing two physical properties, high transparency and high conductivity that are usually mutual exclusive. For the development of novel TCOs the measurement of both dielectric function and optical bandgap are of high priority and as well the study of their vibrational properties. Optical spectrophotometry and Spectroscopic ellipsometry (SE) are two non-destructive and versatile characterization techniques commonly used for the characterization of optical properties of TCOs. We discuss here the methodology for the accurate determination of both dielectric function and optical bandgap. This requires a complex approach and the benefits and pitfalls of either using optical spectrophotometry or spectroscopic ellipsometry are considered in details. The experimental determination of the optical dielectric function over a large spectral range from UV to Far IR, optical bandgap and vibrational properties inferred from combined approach involved Infrared Ellipsometry, Raman and IR spectroscopy, for several n and p-type TCOs is discussed and results are then compared with theoretical calculations.