
Black phosphorus could spur the next wave of tiny transistors (2015) - peter_d_sherman
https://newatlas.com/black-phosphorus-next-gen-microchips/38378/
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peter_d_sherman
>"Graphene is a one-atom thick material with high electrical conductivity, but
as a zero bandgap semiconductor, it acts like a metal. This means that
transistors made of the material cannot be easily turned on and off.

Black phosphorus also can be separated into one-atom thick layers known as
phosphorene. Unlike graphene, phosphorene acts as a semiconductor that can
easily be switched on and off."

Disclaimer: I don't know if Graphene does or doesn't make a good
semiconductor, but I think it's interesting to have alternatives to Silicon
other than GaAs or Graphene, and Phosphorene, if the claims turn out to be
true, could very well be one such alternative...

~~~
MayeulC
Well, every material in column IV of the periodic table (Carbon, Silicon...)
is a semiconductor. You basically want to have enough electrons, but not too
much.

Electron density can be adjusted by adding atoms that have too many (column V,
on the right), or too few (column III, on the left). Hence III-V
semiconductors, like GaAs. You'll notice that Germanium is used as well in
some applications (fast, expensive circuits for high frequency applications
such as RF).

By combining those together, you can obtain a range of properties. I think
phosphorus was already used, but the insight here is probably that it is 2D.

The way MOS transistors work is that you have a semiconductor that is really
just a bad conductor (so it could be made starting from most conductors,
"doping" them to conduct less with atoms that trap electrons). By putting an
electric field across the semiconductor, electrons will gather together near
the positive electrode. Electron density is now enough to meaningfully
conduct. So "semiconductor" is just walking a fine line between conducting and
not conducting :)

~~~
peter_d_sherman
>"Well, every material in column IV of the periodic table (Carbon, Silicon...)
is a semiconductor. You basically want to have enough electrons, but not too
much."

Excellent point!

While I have your attention, let me advance a "crackpot theory" (Note that
this is theoretical only, and completely unproven!): The "crackpot theory"
goes something like this:

Perhaps _every_ element, not just those on column IV of the periodic table --
is in fact a semiconductor (just that we don't know it currently), but VOLTAGE
must vary by element, as must the spacing of entry/exiting conductors -- to
get this semiconductor effect in any given element...

For metals which conduct normally, VOLTAGE needs to be extremely low, for
semiconductors, it needs to be higher, and for apparently non-conducting
materials -- much higher still (VOLTAGE will conduct across any material if
you make it high enough).

You see, VOLTAGE is the original "conductor", regardless of underlying
material (the underlying material can just be thought of as a waveguide of
sorts).

 _Want a conductor? Raise the voltage high enough for the underlying material.
Want a semiconductor? Lower voltage so that the circuit still conducts a
little bit of current, and at a certain slightly lesser point stops. Want an
insulator? Lower voltage some more until you have one._

In any given underlying material, the voltage necessary to accomplish any of
these three things will vary, sometimes radically, material to material (i.e.,
apparent "conductor" to apparent "non-conductor").

Anyway, that's the theory.

I haven't been able to prove it or disprove it; it's theoretical only at this
point.

Also, another key point is that once a substance is electrified, that is, once
there is a circuit path established through it (or perhaps around it, if its
resistance is higher than air), but once a circuit path is established, the
voltage necessary to sustain the circuit from that point forward is usually
less than the voltage needed to create it.

Simple example: Xenon flash bulb. Xenon gas acts like an insulator to low
voltages. It takes a high voltage initial pulse to get it going, but then as
it draws current, the voltage to sustain the circuit can be lower. The same
with florescent bulbs.

Then we have this extremely wierd concept called "ionization". We claim that
somehow, if something becomes electrically conductive, it's because of "ions",
as opposed to just plain voltage.

Well, "just plain voltage" high enough, relative to the resistance of the
underlying material -- is what starts the circuit off in the first place...
it's a far simpler explanation than 'ions'...

Get a Tesla coil, and you'll see that that the high-voltage electricity it
produces -- is conducted by so-called non-conductors, even such things as
wood... that is, to a tesla coil, wood becomes a conductor, not an
insulator...

So what is 'doping' then, if there are no ions?

Well, think of all materials as memristors of sorts.

Running various types of voltage through various types of material in a given
direction one time -- changes the breakdown voltage the next time a current-
carrying voltage is applied.

Now, this effect varies by material, by length, and by amount of voltage
applied, and for how long it is applied for.

But this "memristor" effect -- would be the equivalent of what today is called
"doping" \-- if it existed, and I claim (but cannot prove, because
experimentation is necessary) that logically, logically, there is evidence to
support this (for diodes/transistors, it's called "diode/transistor biasing".
Well, "biasing" = "doping" = "applying voltage and then turning it off to
change (if ever so slightly) the electrical characteristics of the underlying
medium (if ever so slight) for the next time a current-carrying voltage is
applied"

Anyway, that's the crackpot theory.

Voltage.

Someone probably discovered that a long time ago and it was forgotten in
history as newer trendier concepts were developed...

I'm not saying that any of the above theorizing is true; I'm just saying that
based on logic, it seems logical...

Someone will have to prove or disprove it via experimentation...

But, if it's true, then maybe _every single element and chemical compound
could be used to create transistors in the future_ \-- it's just that at this
point in our history, humanity doesn't know how to do this exactly yet...

If it's true...

If not, well then, "I am a crackpot"... <g>

------
Communitivity
I suspect the reason this may be trending again is the 'Black Nitrogen' was
just discovered. So called because of its similarities to 'Black Phosphorous',
it is the only known allotrope of Nitrogen other than Ninitrogen,and the only
one that has properties similar to elements on the periodic table row
underneath Nitrogen. It show good conductivity too, but researchers are unable
to stabilize it so commercial uses are out until they do.

[https://phys.org/news/2020-06-black-nitrogen-high-
pressure-m...](https://phys.org/news/2020-06-black-nitrogen-high-pressure-
material-puzzle.html)

