RESONANT-TUNNELING AND INTRINSIC BISTABILITY IN GASB-BASED DOUBLE-BARRIER HETEROSTRUCTURES

The two main consequences of resonant tunneling in semiconductor heter ostructures are the existence of negative differential resistance and of bistability in their current-voltage (I-V) characteristics. While t he presence of the former validated the first experimental claim of re sonant 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 bee n observed in GaAs-GaAlAs heterostructures, but the assertion that the observation is intrinsic to the resonant-tunneling process and not du e to extrinsic effects such as parasistic series resitance has been di sputed [Goldman et al., Phys. Rev. Lett. 58, 1622 (1987); Sollner, Phy s. Rev. Lett. 59, 1622 (1987)]. The application of a magnetic field to asymmetric heterostructures has firmly established that intrinsic bis tability can be observed [Zaslavsky et al., Appl. Phys. Lett. 53, 1408 (1988)] and seems to have put the controversy to rest. But, on the ot her hand, under more conventional conditions (no magnetic field, symme tric structures) it is difficult to decide on the origin of bistabilit y, at least in GaAs-GaAlAs resonant-tunneling diodes. We demonstrate h ere that, because of their unique band structure, such an ambiguity do es not exist in GaSb-AlSb diodes: the observed bistability is unequivo cally intrinsic.