Open AccessModeling the dielectric function of degenerately doped ZnO:Al thin films grown by ALD using physical parameters
Author(s) -
Michael Latzel,
Manuela Göbelt,
Gerald Brönstrup,
Cornel Venzago,
Sebastian W. Schmitt,
George Sarau,
Silke Christiansen
Publication year - 2015
Publication title -
optical materials express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 66
ISSN - 2159-3930
DOI - 10.1364/ome.5.001979
Subject(s) - materials science , photoluminescence , atomic layer deposition , doping , thin film , indium , optoelectronics , dielectric , ellipsometry , transparent conducting film , fermi level , optics , nanotechnology , physics , quantum mechanics , electron
Transparent conductive thin films are a key building block of modern optoelectronic devices. A promising alternative to expensive indium containing oxides is aluminum doped zinc oxide (AZO). By correlating spectroscopic ellipsometry and photoluminescence, we analyzed the contributions of different optical transitions in AZO grown by atomic layer deposition to a model dielectric function (MDF) over a wide range of photon energies. The derived MDF reflects the effects of the actual band structure and therefore describes the optical properties very accurately. The presented MDF is solely based on physically meaningful parameters in contrast to empirical models like e.g. the widely used Sellmeier equation, but nevertheless real and imaginary parts are expressed as closed-form expressions. We analyzed the influence of the position of the Fermi energy and the Fermi-edge singularity to the different parts of the MDF. This information is relevant for design and simulation of optoelectronic devices and can be determined by analyzing the results from spectroscopic ellipsometry. (C) 2015 Optical Society of Americ