About VT(threshold voltage) of MOS

[xhwubai]

Homework Statement

(1)what's the relationship between VT and channel length, width?
(2)In the formula of VT, when calculation of oxide capacitor voltage, namely, Vox=Q(inv)/Cox
, why Cox is per square capacitance?

Homework Equations

3. Thank you very much!

 

[runo]

1)-The relationship between Vt and the channel length is called short channel effect. If you search on the web you can find enough information. The third term in your equation needs a modification to see the relation between Vt and L.
2)- Cox's units can be modified depend on the units of the charges density. The aim is to get volts out of the devision.