Electroluminescence and photoluminescence of type-II InAs/InAsSb strained-layer superlattices in the mid-infrared

There is continuing interest in the development of superlattices for use in photonic devices operating in the technologically important mid-infrared spectral range. In this work type-II strained-layer superlattices of InAs/InAs1-xSbx (x = 0.04 and x = 0.06) were grown on InAs (1 0 0) substrates by MBE. Structural analysis of the samples revealed good crystalline quality but a non-uniform distribution of Sb within the QWs which originated from segregation effects during growth. Bright photoluminescence emission was obtained at low temperature (4 K) which persisted up to 300 K. Two prototype samples were grown containing the corresponding superlattices in the active region and fabricated into LEDs. Mid-infrared electroluminescence was obtained from both these LEDs over the temperature range 7-300 K and both devices exhibit emission coincident with the main CO2 absorption band near 4.2 μm at room temperature. These LEDs produced output powers of 8.2 µW and 3.3 µW under 100 mA injection current at room temperature and are of interest for CO2 detection and further development for mid-infrared gas sensing applications.