Resonant tunneling and intrinsic bistability in GaSb-based double barrier heterostructures

The two main consequences of resonant tunneling in semiconductor heterostructures are the existence of negative differential resistance and of bistability in their current-voltage (I-V) characteristics. While the presence of the former validated the first experimental claim of resonant tunneling in semiconductors [Chang et al., Appl. Phys. Lett. 24, 593 (1974)] and has been the trademark of the phenomenon ever since, intrinsic bistability has been much more elusive. Bistability has been observed in GaAs-GaAlAs heterostructures, but the assertion that the observation is intrinsic to the resonant-tunneling process and not due to extrinsic effects such as parasistic series resitance has been disputed [Goldman et al., Phys. Rev. Lett. 58, 1622 (1987); Sollner, Phys. Rev. Lett. 59, 1622 (1987)]. The application of a magnetic field to asymmetric heterostructures has firmly established that intrinsic bistability can be observed [Zaslavsky et al., Appl. Phys. Lett. 53, 1408 (1988)] and seems to have put the controversy to rest. But, on the other hand, under more conventional conditions (no magnetic field, symmetric structures) it is difficult to decide on the origin of bistability, at least in GaAs-GaAlAs resonant-tunneling diodes. We demonstrate here that, because of their unique band structure, such an ambiguity does not exist in GaSb-AlSb diodes: the observed bistability is unequivocally intrinsic.