Cascaded InGaSb quantum dot mid-infrared LEDs.

We demonstrate cascaded, mid-infrared light-emitting diodes with quantum dot based active regions. Cascading is achieved through highly reverse-biased AlInAsSb tunnel junctions that serve to connect the successive InGaSb quantum dot active regions. Temperature-dependent characterization of the output irradiance as a function of the current and voltage indicates that the cascade architecture has minimal leakage currents in contrast to earlier single-stage devices and provides carrier recycling with a concomitant increase in irradiance. The results show that cascaded architectures can be applied to quantum dot platforms and that the quantum efficiency of the active region limits the overall device efficiency. [ABSTRACT FROM AUTHOR]