High-performance InAs/GaSb superlattice photodiodes for the very long wavelength infrared range

We report on the demonstration of high-performance $\mathrm{p-i-n}$ photodiodes based on type-II InAs/GaSb superlattices with 50% cut-off wavelength ${\lambda }_c\text{=16}$ μm operating at 80 K. Material is grown by molecular beam epitaxy on GaSb substrates with excellent crystal quality as evidenced by x-ray diffraction and atomic force microscopy. The processed devices show a current responsivity of 3.5 A/W at 80 K leading to a detectivity of ${\text{∼1.51×10}}^{10}$ ${\mathrm{cmHz}}^{\mathrm{1/2}}\mathrm{/W}.$ The quantum efficiency of these devices is about 35% which is comparable to HgCdTe detectors with a similar active layer thickness.