Indium tin oxide on copper phthalocyanine – an ellipsometry study

Abstract

AbstractSpectroscopic ellipsometry was employed to evaluate the influence of ITO deposition on underlying copper phthalocyanine (CuPc) thin films grown on silicon with native oxide. At first the dielectric functions of ITO and copper phthalocyanine were derived from a multi‐sample analysis of single layer samples. While the CuPc films were isotropic in the substrate plane they showed a strong anisotropy in their optical response perpendicular to the film plane. Obvious higher values were observed below 1.9 eV for the real part, and over the whole spectral range (0.7 – 5 eV) for the imaginary part of the dielectric function perpendicular to the film plane. The dielectric functions were applied to model the double layer samples with ITO on top, resulting in a good match of modelled and measured ellipsometry spectra. This is a clear indication that the ITO deposition does not destroy or strongly modify the optically anisotropic CuPc layer. In a next step the CuPc dielectric function was varied to improve the fit resulting in a slight line shape change. This change might be a hint for possible phase transformation of a small part of the CuPc from α to β phase due to ITO deposition. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)