We experimentally demonstrate negative differential resistance, collector current oscillations, and light emission in a transistor-injected quantum cascade structure. Distinct transport regimes are accessed by varying the reverse bias across the base-collector junction while independently controlling emitter injection. The collector current shows pronounced oscillations and alternating high–low levels as the reverse bias changes, indicating quantum transport through the superlattice. Oscillations at a peak frequency of 3.2 MHz occur within high-bias negative differential resistance regions. Spontaneous short-wave infrared (SWIR) emission from the base region is characterized using Fourier transform infrared spectroscopy, revealing a peak wavelength of 1.58 m. Coupling between the emitted light and superlattice modes is confirmed by SWIR intensity oscillations synchronized with collector current oscillations. Under forward bias of the base-collector junction, the device emits coherent SWIR light at 1.58 m, aided by carrier confinement from a quantum impedance matching region. Additionally, spontaneous mid-wave infrared emission is observed from the quantum cascade structure. This three-terminal, transistor-injected platform integrates electronic modulation with tunable optical output, showing promise for a versatile alternative to conventional two-terminal quantum cascade devices that could enable new opportunities in long-wavelength photonics for sensing, communication, and spectroscopy applications.

https://www.doi.org/10.1007/s00340-026-08676-3

Bistability in the current–voltage characteristics of semiconductor superlattices and quantum cascade laser structures has the potential for wide-ranging applications, particularly in sensing systems. However, the interdependency of applied bias and current injection in conventional two-terminal structures has led to complications in analysis and rendered the bistability phenomenon difficult to implement in practical applications. Here, we report a new kind of electronic bistability coupled to optical switching in a resonant tunneling bipolar superlattice transistor. This bistability manifests as sharp discontinuities in the collector current with extremely small variations of the applied voltage, which arise from unstable tunneling transmission across the hetero-barrier between the two-dimensional electron gas (2DEG) at the edge of the transistor base and the collector superlattice structure. The electronic transitions between high and low quantum mechanical transmissions are demonstrated to be caused by self-consistent variations of the internal electric field at the heterointerface between the 2DEG and the superlattice. They are also present in the base current of the three-terminal device and result in sharp switching of near-infrared spontaneous light emission output from an interband radiative recombination process with a peak emission wavelength of 1.58  m. A comprehensive quantum mechanical theoretical model accounting for the self-consistent bistable tunneling transmission is in quantitative agreement with the experimental data. The measured peak transconductance sensitivity value of 6000 mS can be used in the highly sensitive detector and non-linear device applications.

https://doi.org/10.1063/5.0190385