How does zirconium-oxide coating reduce work function in SEM tips?

In summary, the conversation discusses the use of scanning electron microscopy and the coating of the SEM tip with zirconium-oxide to lower the work function. The mechanism behind this reduction and the influence of surface effects are explained, with a reference to a book for further understanding.
  • #1
teaforone
4
0
Hi Folks,
I have been studying some scanning electron microscopy and read that the SEM tip is made from tungsten but is coated with a mono-layer of zirconium-oxide to reduce the work function from 4.5ev to 2.7ev, to make it easier to emit electrons (this is a field emission SEM).

Does anyone have any idea how this reduction in work function occurs? What is the physical mechanism and what is occurring at the interface between the two substances to lower the work function? Any references or links to help me comprehend this would be greatly appreciated.

Thanks.
 
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  • #2
Work function and it's dependency on surface effects is well explained in Ashcroft Mermin, Solid state physics.
Basically there are two important factors: 1. The Fermi energy of the metal, 2. The dipole potential at the surface.
The latter one can be influenced by a surface layer.
 
  • #3
Thank you DrDu, I'll try to check that out.
 

What is work function reduction?

Work function reduction is the process of reducing the amount of energy required to remove an electron from a material's surface. It is typically achieved by altering the surface properties of the material through various methods.

Why is work function reduction important?

Work function reduction is important because it can significantly improve the efficiency of electronic devices by reducing the energy needed for electron emission. This can lead to lower power consumption and better overall performance.

What are some methods for achieving work function reduction?

Some common methods for achieving work function reduction include doping the material with impurities, applying a thin film coating, and using surface treatments such as plasma etching or ion bombardment.

What are some applications of work function reduction?

Work function reduction has many applications in electronic devices, including solar cells, field emission displays, and electron sources for particle accelerators. It is also used in various types of sensors and detectors.

Are there any potential drawbacks to work function reduction?

One potential drawback of work function reduction is that it can make the material more susceptible to degradation and contamination. It can also affect the material's electronic properties, so careful consideration must be given to the specific application and materials used.

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