A Sensitive and Versatile Thickness Determination Method Based on Non-Inflection Terahertz Property Fitting
The accuracy of thin-film characterization in terahertz spectroscopy is mainly set by the thickness uncertainty. Physical thickness measurement has limited accuracy for thin-film samples thinner than a few hundreds of micrometers and is sometimes even impossible. The temporal resolution of time-doma...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2019-09-01
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| Series: | Sensors |
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| Online Access: | https://www.mdpi.com/1424-8220/19/19/4118 |
| _version_ | 1818034824460369920 |
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| author | Xuequan Chen Emma Pickwell-MacPherson |
| author_facet | Xuequan Chen Emma Pickwell-MacPherson |
| author_sort | Xuequan Chen |
| collection | DOAJ |
| description | The accuracy of thin-film characterization in terahertz spectroscopy is mainly set by the thickness uncertainty. Physical thickness measurement has limited accuracy for thin-film samples thinner than a few hundreds of micrometers and is sometimes even impossible. The temporal resolution of time-domain terahertz spectrometers is not sufficient to resolve such thin films. Previously reported numerical methods mainly only work for materials with low dispersion and absorption. Here, we propose a novel method for thickness determination by fitting a non-inflection offset exponential function to the material optical properties. Theoretical analysis predicts the best fitting to only be achieved when the correct thickness is given. Transmission measurements on a thin-film polymer, water, and a lactose pallet verify the theory and show the accurate thickness determination and property characterization on materials which are either achromatic or dispersive, transparent or absorptive, featureless or resonant. The measurements demonstrate the best versatility and sensitivity compared to the state-of-art. The method could be widely adapted to various types of research and industrial applications. |
| first_indexed | 2024-12-10T06:45:18Z |
| format | Article |
| id | doaj.art-75c94bdd12b943369dfae83c6fbecbd7 |
| institution | Directory Open Access Journal |
| issn | 1424-8220 |
| language | English |
| last_indexed | 2024-12-10T06:45:18Z |
| publishDate | 2019-09-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Sensors |
| spelling | doaj.art-75c94bdd12b943369dfae83c6fbecbd72022-12-22T01:58:40ZengMDPI AGSensors1424-82202019-09-011919411810.3390/s19194118s19194118A Sensitive and Versatile Thickness Determination Method Based on Non-Inflection Terahertz Property FittingXuequan Chen0Emma Pickwell-MacPherson1Department of Electronic Engineering, The Chinese University of Hong Kong, Hong Kong 999077, ChinaDepartment of Electronic Engineering, The Chinese University of Hong Kong, Hong Kong 999077, ChinaThe accuracy of thin-film characterization in terahertz spectroscopy is mainly set by the thickness uncertainty. Physical thickness measurement has limited accuracy for thin-film samples thinner than a few hundreds of micrometers and is sometimes even impossible. The temporal resolution of time-domain terahertz spectrometers is not sufficient to resolve such thin films. Previously reported numerical methods mainly only work for materials with low dispersion and absorption. Here, we propose a novel method for thickness determination by fitting a non-inflection offset exponential function to the material optical properties. Theoretical analysis predicts the best fitting to only be achieved when the correct thickness is given. Transmission measurements on a thin-film polymer, water, and a lactose pallet verify the theory and show the accurate thickness determination and property characterization on materials which are either achromatic or dispersive, transparent or absorptive, featureless or resonant. The measurements demonstrate the best versatility and sensitivity compared to the state-of-art. The method could be widely adapted to various types of research and industrial applications.https://www.mdpi.com/1424-8220/19/19/4118thin-film characterizationthickness uncertaintyinflection pointexponential functionfitting |
| spellingShingle | Xuequan Chen Emma Pickwell-MacPherson A Sensitive and Versatile Thickness Determination Method Based on Non-Inflection Terahertz Property Fitting Sensors thin-film characterization thickness uncertainty inflection point exponential function fitting |
| title | A Sensitive and Versatile Thickness Determination Method Based on Non-Inflection Terahertz Property Fitting |
| title_full | A Sensitive and Versatile Thickness Determination Method Based on Non-Inflection Terahertz Property Fitting |
| title_fullStr | A Sensitive and Versatile Thickness Determination Method Based on Non-Inflection Terahertz Property Fitting |
| title_full_unstemmed | A Sensitive and Versatile Thickness Determination Method Based on Non-Inflection Terahertz Property Fitting |
| title_short | A Sensitive and Versatile Thickness Determination Method Based on Non-Inflection Terahertz Property Fitting |
| title_sort | sensitive and versatile thickness determination method based on non inflection terahertz property fitting |
| topic | thin-film characterization thickness uncertainty inflection point exponential function fitting |
| url | https://www.mdpi.com/1424-8220/19/19/4118 |
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