Observation of N- and S-shaped negative differential resistance behavior in AlGaAs/GaAs resonant tunneling structure

Abstract

A MBE-grown two-terminal GaAs device with AlGaAs/GaAs quantum wells embedded in the base of a heterojunction bipolar transistor structure exhibiting both S-shaped and N-shaped negative differential resistance (NDR) characteristics is demonstrated. Due to the asymmetric structure, both S-and N-shaped NDR behaviors can be observed in the same device depending on the polarity applied. The S-shaped NDR behavior is explained by the enhancement of an avalanche process while the N-shaped NDR characteristics is attributed to a resonant tunneling process. The effects of band offset of AlGaAs/GaAs in the emitter/base and/or base/collector junction are found to have profound influence on the device characteristics and will be discussed.