# Mosfet electron velocity.

Discussion in 'Homework Help' started by Ledwardz, Jan 6, 2013.

1. ### Ledwardz Thread Starter Member

Oct 31, 2010
37
2
Hi folks, stuck again.

Calculate the electron velocity in a MOSFET of length 1μM when a potential difference of 2.5 V is applied assuming channel is doped at 10^17 cm^-3

Okay so my equation for velocity is

v(velocity) = mobility x Electric field.

I come to the conclusion that the electric field was simply voltage over channel length. E = 2.5 x 10^6 V/M

I then assumed that the overall charge in the inversion channel was 10 ^17 multiplied by the length of the channel. Once converted into M that gave me a capacitance of 4x10^-19 F. I know a farad is huge but even then i dont think this can be right????

so supposing that is right i can use the Cox = ε0εox / Tox to figure out Tox

I know the equation for transconductance involves mobility but i cant work out transconductance so this method is screwed.

damn okay i dont know where to go from here. Or if any of that is even right??

any help appreciated.

Thanks,

Lee.