# B Electron as Wave

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1. Sep 15, 2015

### Yashtir Gopee

Hello All,

From my A'Level knowledge of Physics, an electron is both a particle and a wave but not both at the same time.
I would like to know when does an electron behave as a wave (if it does) in a transistor?

Thanks
Yashtir Gopee

2. Sep 15, 2015

### Staff: Mentor

3. Sep 15, 2015

### Yashtir Gopee

The electron has a radius of 10^-16m. Does it oscillate and how much is its displacement?
Actually I would like to know till how much can we reduce the size of a transistor (assuming we get the appropriate materials and environment for the current limitations).

4. Sep 15, 2015

### Staff: Mentor

You are misunderstanding what you've read. The best measurements we have say that whatever the electron's radius is, it's something less than $10^{-22}$ meters. This is consistent with it being a point particle of size zero (to the extent that "size" is even a meaningful concept for a quantum object such as an electron).

There are indeed quantum mechanical limits to how small a transistor can be made, but to understand them you need to understand the quantum mechanical description of electrons.

When you ask about the radius and the displacement and whether the electron oscillates, you're thinking in terms the popular English-language meaning of the word "particle", as if the electron is some sort of little tiny object like a ball with an electric charge. However, the word "particle" has a completely different meaning in quantum mechanics (it's a historical accident that we use the word "particle" to describe these quantum objects), so none of this thinking applies.

5. Sep 15, 2015

### Staff: Mentor

The literature talks about sizes on the order 90 nm for a CMOS transistor:

http://www.monolithic3d.com/blog/is-there-a-fundamental-limit-to-miniaturizing-cmos-transistors1

and on wikipedia there's a discussion on electron size:

https://en.wikipedia.org/wiki/Electron

and then there's Moore's law which is really an observation of industry trends:

https://en.wikipedia.org/wiki/Moore's_law

6. Sep 15, 2015

### DrChinese

Welcome to PhysicsForums, Yashtir!

The electron does not oscillate in the normal sense of the word. True, it has a property call "spin" but that is a misleading word. Please keep in mind that the electron is a quantum particle. That means that it operates by the rules of quantum mechanics and quantum field theory. The descriptive words do not accurately describe what is best described mathematically.

So words like size and spin do not have meaning as you would expect. There is no theoretical lower limit on the size of the electron, so it is often described as a point particle (as already stated by Nugatory and others). It is just as accurate (and as meaningless) to state that a free electron is the size of the universe. Again, it is a quantum particle and all quantum particles have similar descriptive problems.

This is why Nugatory says there are limits to transistor size reduction. Within materials, there are field effects to consider which are well outside the "normal" properties of individual particles.

7. Sep 15, 2015

### Yashtir Gopee

Maybe I'm going a little off-topic now,
Do you guys think continuing Moore's Law is worth it or should we consider alternatives such as 3D IC, DNA Computing(if we want to continue with classical computing) or Quantum Computing?

I wrote an article 2 years back. Have a look through it http://www.yashtechblog.me/the-future-of-computing/

If it is innacurrate, please tell me.

8. Sep 15, 2015

### Staff: Mentor

Indeed you are. This thread is closed.