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Metal semiconductor contact
This document discusses metal-semiconductor interfaces, specifically rectifying Schottky junctions and non-rectifying ohmic contacts. It provides energy band diagrams to illustrate how Schottky junctions form a barrier under reverse bias but allow thermionic emission under forward bias, while ohmic contacts have matching work functions allowing current to flow freely. Applications of Schottky diodes mentioned include RF mixing and solar cells.
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Metal semiconductor contact
- 1. Metal semiconductor contact ANCHITBISWAS TECHNO INDIA ,SALTLAKE
- 2. Metal-Semiconductor Interfaces Rectifying(Schottky Junction) Non-Rectifying (Ohmic Contacts)
- 3. Metal-Semiconductor Interfaces Rectifying(Schottky Junction) Non-Rectifying (Ohmic Contacts)
- 4. Metal-Semiconductor Interfaces Rectifying(Schottky Junction) Non-Rectifying (Ohmic Contacts)
- 5.
- 6. How Schottky JunctionWorks ? Energy band diagram of an isolated metal adjacent to an isolated n-type semiconductor n type
- 7. How Schottky JunctionWorks ? Energy band diagram of an isolated metal adjacent to an isolated n-type semiconductor Energy band diagram of a metal-n semiconductor contact in thermal equilibrium n type Metal n type semiconductor
- 8. How Schottky JunctionWorks ? Energy band diagram of an isolated metal adjacent to an isolated n-type semiconductor Energy band diagram of a metal-n semiconductor contact in thermal equilibrium n type
- 9. How Schottky JunctionWorks ? Under forward bias condition n type Thermionic -emission
- 10. How Schottky JunctionWork ? Under forward bias condition Under reverse bias condition n type n type Thermionic -emission
- 11.
- 12. Advantages of SchottkyDiode Low turn on voltage Fast recovery time Low junction capacitance
- 13. Applications of SchottyDiode RF mixer and detector diode solar cell applications etc
- 14. How Ohmic ContactWorks ? Energy band diagram of an isolated metal adjacent to an isolated n-type semiconductor n type
- 15. How Ohmic ContactWorks ? Energy band diagram of an isolated metal adjacent to an isolated n-type semiconductor n type Energy band diagram of a metal-n semiconductor contact in thermal equilibrium
- 16. How Ohmic ContactWorks ? Under forward bias condition
- 17. How Ohmic ContactWorks ? Under forward bias condition Under reverse bias conditon
- 18.
Editor's Notes
- #10 n a rectifying Schottky barrier, the barrier is high enough that there is a depletion region in the semiconductor, near the interface. This gives the barrier a high resistance when small voltage biases are applied to it. Under large voltage bias, theelectrical current flowing through the barrier is essentially governed by the laws of thermionic emission, combined with the fact that the Schottky barrier is fixed relative to the metal's Fermi level.[3] Under forward bias, there are many thermally excited electrons in the semiconductor that are able to pass over the barrier. The passage of these electrons over the barrier (without any electrons coming back) corresponds to a current in the opposite direction. The current rises very rapidly with bias, however at high biases the series resistance of the semiconductor can start to limit the current. Under reverse bias, there is a small leakage current as some thermally excited electrons in the metal have enough energy to surmount the barrier. To first approximation this current should be constant (as in the Shockley diode equation), however current rises gradually with reverse bias due to a weak barrier lowering (similar to the vacuumSchottky effect). At very high biases, the depletion region breaks down. (the discussion above is for a Schottky barrier to an n-type semiconductor; similar considerations apply for a p-type semiconductor) The current-voltage relationship is qualitatively the same as with a p-n junction, however the physical process is somewhat different.[4]
- #11 n a rectifying Schottky barrier, the barrier is high enough that there is a depletion region in the semiconductor, near the interface. This gives the barrier a high resistance when small voltage biases are applied to it. Under large voltage bias, theelectrical current flowing through the barrier is essentially governed by the laws of thermionic emission, combined with the fact that the Schottky barrier is fixed relative to the metal's Fermi level.[3] Under forward bias, there are many thermally excited electrons in the semiconductor that are able to pass over the barrier. The passage of these electrons over the barrier (without any electrons coming back) corresponds to a current in the opposite direction. The current rises very rapidly with bias, however at high biases the series resistance of the semiconductor can start to limit the current. Under reverse bias, there is a small leakage current as some thermally excited electrons in the metal have enough energy to surmount the barrier. To first approximation this current should be constant (as in the Shockley diode equation), however current rises gradually with reverse bias due to a weak barrier lowering (similar to the vacuumSchottky effect). At very high biases, the depletion region breaks down. (the discussion above is for a Schottky barrier to an n-type semiconductor; similar considerations apply for a p-type semiconductor) The current-voltage relationship is qualitatively the same as with a p-n junction, however the physical process is somewhat different.[4]