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Polytype heterostructures of GaSb/AlSb/InAs show interband tunneling due to the 0.1 eV overlap of the InAs conduction band and the GaSb valence band. This broken-gap configuration results in a novel mechanism for negative differential resistance that has potential applications in high-speed devices. We have demonstrated for the first time interband tunneling in single-barrier and double-barrier polytype heterostructures. Single-barrier structures show negative differential resistance due to the change in interband tunneling with applied bias. A peak-to-valley ratio of 2.7:1 at 77 K was observed in this case. Double-barrier structures using an InAs quantum well exhibit resonant interband tunneling with a peak-to-valley current ratio of more than 60:1 at 77 K. This structure is promising for applications to three-terminal devices because of the very wide quantum well that can be achieved.
Luo et al. (Mon,) studied this question.