On the flow equation in device simulation

The nonlocal effect of an inhomogeneous electric field on the carrier drift velocity is considered with particular reference to n-Si. A field-dependent phenomenological length constant, giving the first-order effect of the field gradient, is discussed in terms of the Boltzmann equation. It is also shown how this constant may be calculated from the actual effect of a small]] step" in an otherwise homogeneous field, by a formula which extends a previously given formula for this case.