Metal-(semi)Metal junctions

  • Thread starter JustinLevy
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In summary, metal-semiconductor junctions can exhibit band bending and charge transfer, but no depletion zone due to the high density of charge carriers in metals. Techniques such as capacitance-voltage measurements and Kelvin probe force microscopy can be used to detect the electric field at the junction. It is possible to create a depletion zone at a metal-semimetal junction and make a field effect transistor known as a MESFET.
  • #1
JustinLevy
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There are three related questions:

1] Consider the junction between two metals of differing work functions. The bands will need to bend to make the fermi-levels match and charge will transfer (in analogy to a metal-semiconductor junction). However, due to the density of charge carriers, there will be no "depletion zone" and no rectification, correct? Is there anyway to electronically notice this electric field at the junction?

2] A semimetal can be thought of as having both positive and negative charge carriers, and usually of low density, because of having a "negative" indirect gap. If we have a contact between a metal and semimetal of unequal work functions, can the bands be bent to cause a "depletion zone" for one charge carrier type, but not the other? Is there anyway to electronically notice this?

3] If the semimetal discussion above is correct, then can the junction be made p-type, and thus have n-p-n ... no current flow in either direction. This seems to suggest one could make a "field effect" like transistor out of just metals! Is there something wrong with this ideas? If not, then I assume it has already been tried. Does anyone know what it is called so I can read up on it?


EDIT: By "electronically notice" I mean measurements done by including such a junction in an electronic circuit. Basically, I'm not interested in any "direct probe" type spectroscopic measurements.
 
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I can provide some insights into your questions about metal-semiconductor junctions and semimetals.

1] You are correct in your understanding that at a metal-semiconductor junction, the bands will bend to match the Fermi levels and charge transfer will occur. However, due to the high density of charge carriers in metals, there will be no depletion zone as seen in semiconductor junctions. This means that there will be no rectification at the junction.

To electronically notice the electric field at the junction, one could use techniques such as capacitance-voltage measurements or Kelvin probe force microscopy. These methods can indirectly measure the electric field at the junction by measuring changes in the capacitance or work function, respectively.

2] Yes, it is possible for the bands to be bent at a metal-semimetal junction to create a depletion zone for one type of charge carrier but not the other. This is known as a Schottky barrier and can be observed in certain metal-semiconductor systems. Again, techniques such as capacitance-voltage measurements or Kelvin probe force microscopy can be used to detect this depletion zone.

3] It is possible to make a field effect transistor using just metals, as long as the metal-semimetal junction can be made to exhibit a Schottky barrier. This type of transistor is known as a metal-semiconductor field effect transistor (MESFET). It has been extensively studied and used in electronic devices such as amplifiers and switches.

I hope this helps answer your questions. If you are interested in learning more, I suggest looking into research papers on metal-semiconductor junctions and MESFETs. These terms should help you find relevant information on this topic.
 

1. What are metal-semimetal junctions?

Metal-semimetal junctions are interfaces between two materials where one is a metal and the other is a semimetal. These junctions exhibit unique electronic and optical properties due to the difference in their electronic structures.

2. What are the applications of metal-semimetal junctions?

Metal-semimetal junctions have various potential applications in fields such as electronics, optoelectronics, and catalysis. They can be used as components in electronic devices, sensors, and photocatalysts for water splitting and CO2 reduction.

3. How are metal-semimetal junctions formed?

Metal-semimetal junctions can be formed by physical methods such as depositing thin layers of metal and semimetal on top of each other, or by chemical methods such as using molecular precursors to grow the materials in a controlled manner.

4. What are the factors affecting the properties of metal-semimetal junctions?

The properties of metal-semimetal junctions are affected by factors such as the materials used, the interface structure, the presence of defects, and the type of bonding between the two materials. These factors can influence the electronic structure and charge transfer at the junction.

5. How can metal-semimetal junctions be characterized?

Metal-semimetal junctions can be characterized using various techniques such as scanning tunneling microscopy, X-ray photoelectron spectroscopy, and electrical measurements. These techniques can provide information about the morphology, chemical composition, and electronic properties of the junction.

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