[extropy-chat] diffraction limit

[Dan Clemmensen]

Brent Neal wrote:

>Because of that, its fairly meaningless to talk about a "minimum dimension above which no tunnelling occurs."  For a given spacing and permittivity, you can talk about the mean time between tunnelling incidents. If that is on the order of 10^10 years, you can safely call that "no tunnelling."  If its 10^-10 seconds, then you can talk about a "tunnelling current." For anywhere in between, you likely care more about whether the tunnelling will allow enough electrons through to cause dielectric breakdown (which is bad) or so few that you can call your device reliable. 
>
>  
>
Thanks, Brent. This is the reason that I avoided this terminology. There 
is a continuum of tunneling from negligible to overwhelming. When 
features are large, tunneling can be neglected when analyzing device 
performance. When features are really small, tunneling is overwhelming 
and classical analysis is useless. We are currently in the range between 
negligible and overwhelming. As of now, we can treat tunneling as a 
funny kind of leakage effect, and otherwise simply use classical 
techniques. What I really want to know is when will tunneling overwhelm 
the classical analysis.

As you may have seen "screrir" found a paper that looks at this issue. 
If I understood the paper correctly, the answer is basically that 
classical electronics cannot be supported for devices that are smaller 
than 20nm in diameter, regardless of the technology.

I have trouble with "hi-K" and "low-K" dielectrics. Apparently, we need 
both, some in some areas, and some in others? From your comment "low-K" 
is good when we want to minimize tunneling.