S
steve
- Jan 1, 1970
- 0
Could anyone explain why hole speed in semiconductor material is less
than electron speed?
TIA
Steve
than electron speed?
TIA
Steve
Could anyone explain why hole speed in semiconductor material is less
than electron speed?
in the transport of an electron and it is this process that slows it
down making it appear heavy.
Could you suggest which book which discuss this? In all of books I've
read they are not discussing it, perhaps it is for higher level
learning?
I would really like to know how it is calculated though.
Do you teach this subject? perhaps I can attend a class which teach
more about this very interesting thing.
steve said:Could anyone explain why hole speed in semiconductor material is less
than electron speed?
TIA
Steve
Roy said:Steve,
The only truly correct answer to a question about why
a theoretical construct has the properties that it has
is that it makes the theory work.
The best theory we have for what is going on is quantum
electrodynamics (QED) which is intractable (not impossible)
for most engineers (myself included). But the results of
that theory applied to semiconductors can be boiled down
to a simpler theory in which there are "holes" that are
visualized to behave as positively charged heavy electrons.
The theory works pretty good, but that doesn't mean
that the holes have objective existence.
They don't
need a reason to be slow, other than that's what the
experiments suggest.
Kevin said:Well, I'm going to quibble a bit here on the technicalities. Solid state
physics (or condensed matter physics) doesn't really require/use QED in
any direct sense. Quantum Mechanics on its own usually sufficient.
Holes are simply a method of noting that certain electrons go in the
other direction.
Arguable, electrons suffer the same fate.
Again, this suggests some sort of lack of theoretical backup. Basic
Quantum Mechanics fully and completely explains why holes have lower
mobility. Experimental support is pretty much a trivial consequence.
Roy said:quibble noted. I won't argue that point. QM is also intractable
for most engineers. Instead, we have a theory involving holes and
currents and densities and numerous empirical constants. Its
wonderful if you have the math skills and believe in QM and can
calculate those constants, but all you've done is explain one theory
by deriving it from another. Qm also has empirical constants (though
not as many) and the only answer as to why those constants have
the value that they have is that it makes the theory work.
yes, I agree. But I didn't want to have to defend it.
I think we be going meta-physical here. Experimental support
is the reason for the existence of QM, QED, etc.
But, I'm eager to see your explanation, using basic qm and
tractable math as to why the holes are slow. I'll bet you
an ayl that less than 1 in 10 of the readers here will be
able to follow it.