Dissociation of indirect excitons: Discontinuity and bistability in the tunnel current of single-barrier heterostructures

We observed a new discontinuity and bistability in the tunnel current of a 12-nm single-barrier GaAs/AlAs p-i-n heterostructure where a system of spat ially separated two-dimensional electron and hole (e-h) layers of equal and tunable density is realized. Both features appear at T less than or simila r to 300 mK and are substantially enhanced in a magnetic field B greater th an or similar to 10 T perpendicular to the layers. They correspond to a dis continuity in the e-h density and in the phase of the current magneto-oscil lations, which we suggest to arise from a transition between indirect excit ons and the uncoupled e-h gases. [S0163-1829(99) 12343-9].