reverse biased diode variable resistance experiment

Yeah, they call it a zener diode!

Jamie-

The effect of changing a diode's reverse bias results in junction capacitance changing. One Varicap data sheet I checked shows lowering capacitance as Voltage increases. I believe the electrons move away from the junction as reverse Voltage increases.

What you describe sounds like an inside-out field effect transistor. I can imagine there might be some variation in resistance, but why do you think it would be superconductive?

One problem is that you may not be able to probe such a small area. You would need to design a device with molecular-sized electrodes. To use the resistance, current must flow, and some of that current might be "injected" into the junction. Now it is sounding like an SCR!

Fred

You may want to read some more about how PN junctions work. The depletion region _widens_ with increased reverse bias potential.

• See Chapter 7, Transistors and Active Circuits by J. G. Linvill and J. F. Gibbons, MgGraw Hill 1961, especially pp158-173.

• Perhaps you better read the whole book.

This variable resistance (of a zener diode) was used as a crude high voltage shunt regulator for PMTs. One manufacturer (Comprobe) of oil well logging sondes utilized conventional silicon diodes as high voltage regulator devices. The diodes had to be selected for appropriate reverse leakage characteristics, a time consuming process resulting in a low yield of usable devices. The leaky diode high voltage regulator was unreliable and extremely temperature unstable, and its use was long ago discontinued.

Hi,

I meant a variable resistance from one section of the anode to another section of the anode, (or one section of the cathode to another section of the cathode) - but not a variable resistance across the junction.

I should study more before I post though you are right (thanks!)

cheers, Jamie

Le Mon, 02 Dec 2013 20:44:04 -0800, Jamie M a écrit:

Ever been in this world since the 5 past decades?

What you describe is nothing but what earth inhabitants call a JFET.

Cool didn't know you can actually use a diode as a JFET (as long as you have access to the die to put on another wire)

cheers, Jamie

Hi,

I was interested in a theoretical superconducting JFET, ie one that doesn't quite fully shut off the current flow, but leaves a surface flow of electrons like a topological insulator for zero resistance flow.

cheers, Jamie

Hi,

In a JFET, if you turn it off, right before it turns off maybe there is a nonlinear resistance spike when the resistance goes down right as the electrons are only conducting on the very outer area. This would make sense as the JFET turns off when the electrons are only conducting on the outer surface of the silicon, so at that point the conduction case is different than if the electrons were traveling within the silicon.

Also to keep the fine balance of electric field necessary for only surface conduction, right before the JFET is turned off, maybe a light could be shone onto the surface to allow surface conduction, even with a fully turned off JFET.

cheers, Jamie

Reading a bit of Linvill?

Nope! Guess it's this guy?

Yes; in a previous posting,i referred to a particular set of pages in his book Transistors and Active Circuits - when responding to musings regarding reversed biased diodes and negative resistance.

Hi,

I unfortunately don't have the book, sounds interesting though. Might take a trip to the library for that one.

cheers, Jamie

Hi,

"Pressure transforms a semiconductor into a new state of matter" [topological insulator]

In this case they used extreme mechanical pressure, but I think voltage pressure could do the same thing for certain materials or metamaterials.

cheers, Jamie