Mid-infrared InAsSb-based nBn photodetectors with AlGaAsSb barrier layers – Grown on GaAs, using an interfacial misfit array, and on native GaSb

• nBn photodetectors were grown on GaAs using an IMF array, and on native GaSb.
• InAsSb absorption regions allowed for cut off wavelengths of around 3.75 μm.
• Dark current densities were close to Rule 07 for both samples.
• Arrhenius plots revealed diffusion limited dark currents for both samples.

InAsSb-based nBn photodetectors were fabricated on GaAs, using the interfacial misfit (IMF) array growth mode, and on native GaSb. At −0.1 V operating bias, 200 K dark current densities of 1.4 × 10−5 A cm−2 (on GaAs) and 4.8 × 10−6 A cm−2 (on GaSb) were measured. At the same temperature, specific detectivity (D*) figures of 1.2 × 1010 Jones (on GaAs) and 7.2 × 1010 Jones (on GaSb) were calculated. Arrhenius plots of the dark current densities yielded activation energies of 0.37 eV (on GaAs) and 0.42 eV (on GaSb). These values are close to the 4 K bandgap of the absorption layers (0.32–0.35 eV) indicating diffusion limited dark currents and small valence band offsets. Significantly, these devices could be used for mid-infrared focal plane arrays operating within the temperature range of cost-effective thermoelectric coolers.