channel length

Discussion in 'Homework Help' started by maheshg, Aug 11, 2010.

  1. maheshg

    Thread Starter New Member

    Aug 11, 2010
    Hey guys I'm reading Vlsi basics.I got one doubt.In nMos FET If Vgs>Vt then why channel length has been created.Because of Vgs the depletion region will increase deeper which will obstruct the Ids current.
  2. Ghar

    Active Member

    Mar 8, 2010
    Why is the depletion region increasing?

    In an NMOS the channel is p-type an source/drain is n-type.

    When you apply a positive voltage to the gate relative to the bulk the electric field attracts electrons under the gate, inside the p-type bulk. When you have a strong enough electric field there is enough electrons there to make a conductive n-type path between source and drain through the channel.
    You inverted the channel from p-type to n-type essentially.