Interband cascade infrared photodetectors with enhanced electron barriers and p-type superlattice absorbers

We present results on the optical and electrical performance of mid-infrared detectors based on interband-cascade structures. These devices include enhanced electron barriers, designed to suppress intraband-tunneling current between stages, and p-doped type-II InAs/GaSb superlattice absorbers. Within the sample set, we examined devices with different absorber thicknesses and doping levels. Carriers are extracted less efficiently in devices with longer absorbers, which is attributed to more band bending within the absorber due to electric charge accumulation. Also, devices with lower-doped (1 × 1017 cm−3) absorbers are found to have better optical and electrical performances than those with higher levels of doping (3 × 1017 cm−3). The overall performance of these devices was superior to previously reported results, with Johnson-noise limited detectivities, at 4.0 μm, as high as 6.0 × 1012 and 2.5 × 1011 Jones at 80 and 150 K, respectively.