Barrier breakdown in a multiple quantum well structure

We explore a regime of unipolar electronic transport in a multiple quantum well structure with very large current discontinuities - up to five orders of magnitude. Magneto-transport experiments reveal different transport regimes. Quantum well impact ionization shifts the structure from a resistive down state, where the current flows through inter-well quantum tunneling, to a highly conductive up state. In the latter regime, the current leaks through a barrier suddenly broken down because of an efficient ionization of the first quantum well.