Ellipsometry is a versatile technique that is used to probe thin films on a substrate.
Method[edit | edit source]
https://www.appropedia.org/Ellipsometry_protocol:_MOST
Introduction[edit | edit source]
This page is specifically about Spectroscopic ellipsometry (SE) on coated glass samples for solar panel encapsulation. These coatings are made specifically to ensure that water and snow slide off the panel easily.
Sample details[edit | edit source]
75 x 25mm coated microscope glass slides
This section will be updated as soon as more information becomes available.
Experimental[edit | edit source]
Two techniques will be used to determine %transmittance and %reflectance between 300nm and 1000nm.
1. Transmission:
The ellipsometer will be oriented at 180 degrees for wavelength vs % transmittance data. This transmittance data can be corroborated using Filmetrics F20-EXR thin-film analyzer
In addition to transmittance the ellipsometric data will have information on optical constants n (refractive index) and k (extinction coefficient). These constants can be further used to determine optical properties of thin films.
2. Variable angle reflectance:
Data on n and k will be collected between 65 and 75 degrees. Three different approaches can be used here to build a robust, accurate model:
a. The transparent sample will have tape on the backside to minimize backside reflections during this measurement.
b. The transparent sample will a roughened backside to minimize backside reflections during this measurement.
c. The model will be built to account for backside reflections.
3. Depolarization
Depending on the data and model fit, a high resolution depolarization scan may be necessary. In transparent samples, backside reflections occur and thus a percentage of light is unpolarized. This additional information can be used to quantify backside reflections and hence gain information on the thin film on a transparent substrate.
Results[edit | edit source]
The deliverables are:
1. %transmittance vs wavelength
2. %reflectance vs wavelength at 65, 70 and 75 degrees
3. optical constants - n, k
4. Ellipsometric data that can be further used to calculate surface, electrical and optical properties.
