Photonic Characterisation of Indium Tin Oxide as a Function of Deposition Conditions

Indium tin oxide (ITO) has recently gained prominence as a photonic nanomaterial, for example, in modulators, tuneable metasurfaces and for epsilon-near-zero (ENZ) photonics. The optical properties of ITO are typically described by the Drude model and are strongly dependent on the deposition conditi...

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Bibliographic Details
Published in:Nanomaterials (Basel, Switzerland) Switzerland), 2023-06, Vol.13 (13), p.1990
Main Authors: Blair, Samuel F J, Male, Joshua S, Cavill, Stuart A, Reardon, Christopher P, Krauss, Thomas F
Format: Article
Language:English
Subjects:
Carrier density
Deposition
Dispersion curve analysis
Drude model
Electric fields
Electric properties
Electrical measurement
Electrical properties
epsilon-near-zero material
Glass substrates
guided mode resonance
Indium
indium tin oxide
Indium tin oxides
Modulators
nanomaterial
Nanomaterials
Optical properties
Oxides
Parameters
Photonics
Plasma frequencies
Spectrum analysis
Structure
Thin films
Tin compounds
transparent conducting oxides
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Summary:Indium tin oxide (ITO) has recently gained prominence as a photonic nanomaterial, for example, in modulators, tuneable metasurfaces and for epsilon-near-zero (ENZ) photonics. The optical properties of ITO are typically described by the Drude model and are strongly dependent on the deposition conditions. In the current literature, studies often make several assumptions to connect the optically measured material parameters to the electrical properties of ITO, which are not always clear, nor do they necessarily apply. Here, we present a comprehensive study of the structural, electrical, and optical properties of ITO and showed how they relate to the deposition conditions. We use guided mode resonances to determine the dispersion curves of the deposited material and relate these to structural and electrical measurements to extract all relevant material parameters. We demonstrate how the carrier density, mobility, plasma frequency, electron effective mass, and collision frequency vary as a function of deposition conditions, and that the high-frequency permittivity (ϵ∞) can vary significantly from the value of ϵ∞ = 3.9 that many papers simply assume to be a constant. The depth of analysis we demonstrate allows the findings to be easily extrapolated to the photonic characterisation of other transparent conducting oxides (TCOs), whilst providing a much-needed reference for the research area.
ISSN:2079-4991
2079-4991
DOI:10.3390/nano13131990