Breakdown of coherence in resonant tunneling through double- barrier heterostructures.

We report measurements of current-voltage characteristics of symmetric and asymmetric AlGaAs/GaAs double-barrier resonant tunneling structures (DBRTS) which exhibit intrinsic bistability. We interpret the data within a self-consistent model which takes into account the space-charge formation in DBRTS and show that the intrinsic bistability is due to the feedback of the electrostatic field of the electrons in the well on the tunneling current density. We argue that the electron- electron interaction in the well destroys the coherence of tunneling.