  Mott's metal-insulator transition at an interface due to band bending is
studied by the density matrix renormalization group (DMRG). We show that the
result can be recovered by a simple modification of the conventional Poisson's
equation approach used in semi-conductor heterojunctions. A novel mechanism of
colossal electroresistance is proposed, which incorporates the hysteretic
behavior of the transition in higher dimensions.
