TY - JOUR
T1 - Ellipsometric characterization of multi-component thin films
T2 - Determination of elemental content from optical dispersion
AU - Varghese, Ronnie
AU - Pribil, Greg
AU - Reynolds, W. T.
AU - Priya, Shashank
N1 - Funding Information:
The authors gratefully acknowledge the financial support from the Air Force Office of Scientific Research (AFOSR) through the Young Investigator Program . We are also greatly indebted to Clayton Loehn for the EPMA/WDS and EDX characterization work conducted at the Department of Geosciences at Virginia Tech and to Matthew Williams of the Department of Statistics at Virginia Tech for assistance with JMP™ statistical analysis.
PY - 2014/1/1
Y1 - 2014/1/1
N2 - This paper provides the correlation between the compositions of a given thin film to its optical dispersion properties. Gladstone-Dale (G-D) relationships have been used in optical mineralogy to relate density of crystalline compounds to their average refractive index. We purport to use a 'reverse' G-D approach and determine the composition of multi-component thin films from their optical properties. As a model system, we focus on complex perovskite ferroelectric thin film and apply the derived relationships to determine the stoichiometry. The wavelength dispersion of refractive index and extinction coefficient of various Pb(Zr,Ti)O3 (PZT) thin films was measured using Variable Angle Spectroscopic Ellipsometry. Elemental compositions were measured using Energy Dispersive X-ray analysis and Electron Probe Micro Analysis. Wemple-DiDomenico, Jackson-Amer, Tauc and Urbach optical relationships and related parameters were used to extract correlations to elemental content. Both theoretical and semi-empirical approaches to calculate the electronic polarizability of PZT were employed and their variation with elemental content was computed. Perovskite tolerance and octahedral factors were also analyzed against the optical and polarizability parameters. Lastly, these factors and relationships were combined to realize a model for predicting the elemental content of a thin film system.
AB - This paper provides the correlation between the compositions of a given thin film to its optical dispersion properties. Gladstone-Dale (G-D) relationships have been used in optical mineralogy to relate density of crystalline compounds to their average refractive index. We purport to use a 'reverse' G-D approach and determine the composition of multi-component thin films from their optical properties. As a model system, we focus on complex perovskite ferroelectric thin film and apply the derived relationships to determine the stoichiometry. The wavelength dispersion of refractive index and extinction coefficient of various Pb(Zr,Ti)O3 (PZT) thin films was measured using Variable Angle Spectroscopic Ellipsometry. Elemental compositions were measured using Energy Dispersive X-ray analysis and Electron Probe Micro Analysis. Wemple-DiDomenico, Jackson-Amer, Tauc and Urbach optical relationships and related parameters were used to extract correlations to elemental content. Both theoretical and semi-empirical approaches to calculate the electronic polarizability of PZT were employed and their variation with elemental content was computed. Perovskite tolerance and octahedral factors were also analyzed against the optical and polarizability parameters. Lastly, these factors and relationships were combined to realize a model for predicting the elemental content of a thin film system.
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U2 - 10.1016/j.tsf.2013.10.174
DO - 10.1016/j.tsf.2013.10.174
M3 - Article
AN - SCOPUS:84890310823
SN - 0040-6090
VL - 550
SP - 239
EP - 249
JO - Thin Solid Films
JF - Thin Solid Films
ER -