Resonant tunneling in high magnetic fields
GaAs/AlGaAs quantum wells can also be incorporated into tunneling structures. Electrical conduction through these structures is dominated by resonant transmission of tunneling electrons through the quantum well when the lowest allowed state in the well is aligned with the source of electrons (the 'emitter'). This resonance is achieved by applying a voltage across the structure and results in a significant peak in the tunneling current.
Our recent work has concentrated on interesting new features observed in high magnetic fields due to the presence of a second quantum well in the structure  and due to unusual tunneling processes at low bias voltages between Landau levels in the emitter and the quantum well . This latter work appears to reveal a new kind of collective excitation of the 2D electrons.
 L D Macks, S A Brown, R G Clark, R P Starrett, M A Reed, M R Deshpande, C J L Fernando, and W R Frensley, 'Resonant Tunneling in Double Quantum Well, Triple Barrier Heterostructures', Physical Review B 54, 4857 (1996).
 S A Brown, L D Macks, T A Fisher and M Emeny, 'Inter-Landau Level Transitions Near The Threshold Of 2D - 2D Tunneling, Physical Review B 56, 1967 (1997).