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Schottky effect questions

Hi,

Perhaps I don't understand Schottky effect so well. Must the metal be a certain thickness? The following page shows some Schottky diode history, which starts with the Cat's Whisker. Must the metal wire (Cat's Whisker) that contacts the semiconductor be so thin? Then there's the point contact Schottky diode that appears to have a thinly deposited metal. Perhaps the diode would work if the deposited metal was not very thick, but wouldn't it at least still rectify to some degree?

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One last question. Would the Schottky effect work if the metal was say, Boron, which has extremely high resistance, ~ 1e+12 times higher than copper?

Thanks for any help, Paul

Reply to
Paul
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It has been over 20 years since my semiconductor physics class, so the recollection may be a bit dim, but:

I believe that the point-contact diode effect and the Schottky effect are different. Point-contact junctions arise because the physical stress on the semiconductor induces an N-type material even though the doping is P, and this forms a (rather poorly controlled) P-N junction with an ohmic contact to the wire. In the Schottky effect the metal contact itself plays a part in the junction, the type of metal is important, and the P-N junction is formed at the interface between the metal and the semiconductor.

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Tim Wescott
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Reply to
Tim Wescott

There's a depletion region on the semiconductor side of a Schottky junction, so the semiconductor has a thickness requirement, but not the metal.

Things made by pushing bits together don't get a CLEAN, high purity junction. Cat's whiskers aren't Schottky diodes.

Boron isn't easy to deposit in a film, so don't expect to see it replacing platinum for Schottky fabrication. You want a clean metal/semiconductor interface, but boron 'soaks in' to silicon.

Reply to
whit3rd

Thanks for the replies. Does anyone have any data on small rectification effects from dissimilar metal junctions? It's well know that copper to copper-oxide creates a junction, but it's also reported that pure dissimilar metals such as nickel plated copper causes small distortions in sensitive equipment. Is a metal to metal junction possible? Normally the depletion width in metals is considered to be zero relative to semiconductors, but it's well know that it's not exactly zero. If the two metals have different workfunctions then is it possible for a very small amount of rectification to occur? I would love to read about this.

Regards, Paul

Reply to
Paul

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