Potential energy vs. fermi level in metal-metal junction under applied field

In summary: Your Name] In summary, the conversation discusses questions related to the work function of metals in contact and in a two metal junction. The answer to the first question explains how the work function can change due to charge transfer at the interface, known as the Schottky effect. The answer to the second question discusses the potential gradient and Fermi level inside the metals, which depends on the work function difference between the two metals and is also affected by the Schottky effect. Further research on Schottky barriers and metal-semiconductor junctions is suggested for a better understanding of these phenomena.
  • #1
SiO2
3
0
Hello,

I have been lurking in the forum for a while. I have couple of questions that I cannot really find an answer to yet. If any of you have idea/suggestion/know of where to look at, I would greatly appreciate.

First question:
Let's put two different work function metal blocks to each other such that they are ohmically contacted. Would you expect the work function of each block in contact configuration to be the same as two separate blocks (pre-contact)? I cannot find a paper on this... Well, if you have a paper on experiment such as work function on either side, that would be even better! I would imagine when they are in contact, charge transfer will occur to equilibrate the fermi level, and hence I would expect one metal to lose electron, another to gain such that the work function would be the same on both sides. In the process, the work function in the contact configuration would be different due to charge transfer.

Second question:
Hypothetically, let's consider a two metal junctions (three metal pieces). Pin the potentials of the left metal and the right metal such that the difference is [tex]\phi[/tex] (visually, you are applying [tex]\phi[/tex] to a metal.) So my understanding is you would expect no electrical potential gradient inside metal? If so, would you expect flat fermi level inside, or gradient fermi level?

I have attached picture in case my post is too wordy (it probably is...)

Thanks (and sorry for stupid questions)!
-SiO2
 

Attachments

  • PF question.jpg
    PF question.jpg
    24.3 KB · Views: 670
Physics news on Phys.org
  • #2


Dear SiO2,

Thank you for your questions. it is always exciting to see curiosity and interest in understanding complex systems. I will try my best to answer your questions based on my knowledge and research experience in the field of surface science and materials physics.

First question:
In the case of two different metal blocks in contact, the work function of each block will not necessarily be the same as two separate blocks. This is because, as you correctly mentioned, charge transfer will occur at the interface to equilibrate the Fermi level. This charge transfer can change the work function of the metals, as it affects the surface dipole and the surface potential. In fact, the work function of a metal can change significantly when it is in contact with a different metal or even a different material such as a semiconductor. This phenomenon is known as the Schottky effect and has been extensively studied in literature. I suggest looking into papers on Schottky barriers and contact potential difference for more information on this topic.

Second question:
In the case of a two metal junction, the potential gradient inside the metals will depend on the work function difference between the two metals. If the work function difference is large, then there will be a significant potential gradient inside the metals, resulting in a non-flat Fermi level. On the other hand, if the work function difference is small, then the potential gradient will also be small, resulting in a nearly flat Fermi level. This is because the work function of a metal determines the energy required to remove an electron from its surface, and this energy difference can create a potential gradient inside the metal. Again, the Schottky effect plays a crucial role here, and I suggest looking into papers on Schottky barriers and metal-semiconductor junctions for a more in-depth understanding.

I hope this helps answer your questions. Please feel free to ask for clarification or more information if needed.
 

1. What is the relationship between potential energy and fermi level in a metal-metal junction?

In a metal-metal junction, the potential energy of the electrons is directly related to the fermi level, which is the energy level at which there is a 50% chance of finding an electron. This means that the higher the fermi level, the higher the potential energy of the electrons in the junction.

2. How does an applied electric field affect the potential energy and fermi level in a metal-metal junction?

When an electric field is applied to a metal-metal junction, the potential energy of the electrons is changed. This is because the electric field causes the electrons to experience a force, which in turn changes their potential energy. The fermi level also shifts in response to the applied field, resulting in a change in the electron distribution in the junction.

3. How do the potential energy and fermi level change as the distance between the metal electrodes in a junction is varied?

The potential energy and fermi level in a metal-metal junction are inversely proportional to the distance between the metal electrodes. As the distance decreases, the potential energy increases and the fermi level shifts towards the higher potential energy side of the junction. This is due to the increased interaction between the electrons in the two metals.

4. What is the significance of the fermi level in metal-metal junctions?

The fermi level is an important concept in metal-metal junctions because it determines the energy at which electrons will occupy states in the junction. This, in turn, affects the electrical and optical properties of the junction, making it a crucial factor in understanding the behavior of these systems.

5. Can the potential energy and fermi level be directly measured in a metal-metal junction?

The potential energy and fermi level cannot be directly measured in a metal-metal junction. However, their effects can be observed through various experiments, such as measuring the electrical conductivity or optical properties of the junction under different conditions. The potential energy and fermi level can also be calculated using theoretical models and simulations.

Similar threads

  • Atomic and Condensed Matter
Replies
1
Views
1K
  • Atomic and Condensed Matter
Replies
3
Views
2K
  • Atomic and Condensed Matter
Replies
2
Views
4K
  • Atomic and Condensed Matter
Replies
3
Views
1K
  • Atomic and Condensed Matter
Replies
1
Views
1K
  • Atomic and Condensed Matter
Replies
3
Views
2K
  • Atomic and Condensed Matter
Replies
1
Views
4K
Replies
2
Views
1K
  • Classical Physics
Replies
10
Views
1K
  • Atomic and Condensed Matter
Replies
11
Views
3K
Back
Top