Permittivity of aluminium

In summary: You take a series of images of a metal surface and map the distance between features on the image. From this information, you can calculate the permittivity.
  • #1
minerva
93
6
Consider a metal such as Al.
How do we look up or determine the relative permittivity of the metal?

Suppose we have some known incident frequency, say about c/500nm for visible light.
We can look up the bulk plasma frequency (3.7 PHz for Al), can it be calculated from that?

For context, what I want to calculate is the desired hole diameter and geometry as a function of the desired filter centre wavelength, in a nanoscale plasmonic hole-grid structure like this.

https://www.intechopen.com/books/pl...ce-plasmon-polaritons-in-cmos-digital-imaging

We know the metal thickness, want to design the appropriate hole spacing and diameter, know the metal chosen, and know the permittivity of the substrate (glass etc) material.
 
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  • #2
minerva said:
Consider a metal such as Al.
How do we look up or determine the relative permittivity of the metal?

Suppose we have some known incident frequency, say about c/500nm for visible light.
We can look up the bulk plasma frequency (3.7 PHz for Al), can it be calculated from that?

For context, what I want to calculate is the desired hole diameter and geometry as a function of the desired filter centre wavelength, in a nanoscale plasmonic hole-grid structure like this.

https://www.intechopen.com/books/pl...ce-plasmon-polaritons-in-cmos-digital-imaging

We know the metal thickness, want to design the appropriate hole spacing and diameter, know the metal chosen, and know the permittivity of the substrate (glass etc) material.

It has been a while since I touched the topic of dielectrics. But as far as I recall, the relative permittivity of a metal is essentially infinite. It is finite, however, for an insulator/semiconductor.
 
  • #3
I think there are some papers reporting measurements on the dielectric response of aluminum as a function of frequency.
 
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  • #4
Useful nucleus said:
It has been a while since I touched the topic of dielectrics. But as far as I recall, the relative permittivity of a metal is essentially infinite.
Not in the optical region.
 
  • #5
Useful nucleus said:
It has been a while since I touched the topic of dielectrics. But as far as I recall, the relative permittivity of a metal is essentially infinite
That's true only at DC. At non-zero frequency, the permittivity is finite, see for example http://muri.lci.kent.edu/References/NIM_Papers/Permittivity/1983_Ordal_optical.pdf

minerva said:
How do we look up or determine the relative permittivity of the metal?
If I remember correctly (it has been many years ago) you can get permittivity numbers from ellipsometry measurements.
 

1. What is the permittivity of aluminium?

The permittivity of aluminium, also known as the dielectric constant, is a measure of the ability of a material to store electrical energy in an electric field. It is typically denoted by the symbol ε and is a dimensionless quantity. The permittivity of aluminium varies depending on the frequency of the electric field and is typically between 3.5-5.5.

2. How does the permittivity of aluminium compare to other materials?

The permittivity of aluminium is relatively high compared to other common materials, such as air and vacuum, which have a permittivity of 1. This means that aluminium is a good insulator and can store a relatively high amount of electrical energy in an electric field.

3. What factors affect the permittivity of aluminium?

The permittivity of aluminium can be influenced by several factors, including temperature, pressure, and the presence of impurities. In general, the permittivity of aluminium decreases with increasing temperature and increasing pressure. The presence of impurities can also affect the permittivity, as they can introduce defects in the material that can alter its ability to store electrical energy.

4. How is the permittivity of aluminium measured?

The permittivity of aluminium can be measured using a variety of techniques, including capacitance measurements, microwave techniques, and spectroscopic methods. These methods involve applying an electric field to a sample of aluminium and measuring the resulting electric displacement, which is then used to calculate the permittivity.

5. Why is the permittivity of aluminium important?

The permittivity of aluminium is an important property in many applications, particularly in the design of electronic devices. It is used to determine the capacitance of capacitors and the performance of insulators in electrical systems. The permittivity of aluminium also plays a role in the design of antennas and other components of wireless communication systems.

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