Investigation of optical and vibrational properties of functional metal oxides
Mircea Modreanu
Tyndall National Institute, University College Cork, Lee Maltings Dyke Parade, Cork,
Ireland;
E-mail:
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.
I 2
-38-
