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Electron mobility in silicon

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usernam

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Why is electron mobility higher than hole mobility in Silicon?
And is this reason why N-MOS on resistance is lower than P-Mos on resistance?

Thnx
 

hi...

The mobility of any particle is actually related to inertia which in turn is directly related the mass of that particle.

The effective mass of electrons in silicon is 0.26 m0 and the effective mass of holes is 0.36 m0.
and also the the scattering time may differ for both carrier types
and hence the mobility of electrons is more than holes.

And secondly, the mobility is directly related to resistance. hence this conclusion is true about the resistance of NMOS / PMOS. However note that this may not always be the case as the fabircation techniques and materials used also effect the resistance.

Thanks...bye
 

How is the effective mass of electrons and holes in silicon calculated. Shouldn't they be equal??
After all a hole is just the absence of an electron rite?
 

Hi,There is difference energy between the hole particle and free electron particle
so always the energy of hole is smaller than electrons by this we deduce that we
must have different effective mass and also mobilities.
 

All particles have mass, in this case the hole have more mass than electron, for this reason the electron mobility is higher than hole mobility. If you want learn more about this topics, you should read this book:

Microelectronics by Millman
 

well you would have learnt that the hole actually acts like a positive charge and hence there is more effective mass when considering a hole
to understand better hole is moving in the valence band and electron in the conduction band
 

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