Electron tunnelling from a quantum well in crossed electric and magnetic fields

The rate of electron tunnelling from a quantum well formed in a heterostructure and subjected to perpendicular de electric and quantizing magnetic fields has been calculated. It has been shown that at a fixed value of magnetic field there exists a threshold value of electric field below which the tunnelling from the well is impossible. If the electric field exceeds the threshold value, the tunnelling rate increases with increasing electric field, but the dependence of the tunnelling rate on the electric field is not smooth because of new Landau levels being engaged, to which electrons can go over. It is exciting that the tunnelling rate in crossed electric and magnetic fields can be significantly higher than the rate in the presence of just the electric field. A physical explanation of this effect is given.