Type II InAs/GaSb superlattice photovoltaic detectors with cutoff wavelength approaching 32 μm

We report the most recent advance in the area of type II InAs/GaSb superlattice photovoltaic detectors that have cutoff wavelengths beyond 25 μm, with some at nearly 32 μm. The photodiodes with a heterosuperlattice junction showed Johnson noise limited peak detectivity of 1.05×1010 cm Hz1/2/W at 15 μm under zero bias, and peak responsivity of 3 A/W under −40 mV reverse bias at 34 K illuminated by ∼300 K background with a 2π field-of-view. The maximum operating temperature of these detectors ranges from 50 to 65 K. No detectable change in the blackbody response has been observed after 5–6 thermal cyclings, with temperature varying between 15 and 296 K in vacuum.