Fig. 3: Optical performance of the LWIR T2SL phototransistor.
From: Band-structure-engineered high-gain LWIR photodetector based on a type-II superlattice

a Saturated responsivity spectra of the device at 77K and Vb=220mV. b The variation in the responsivity at 6.8µm versus the applied bias voltage (Vb)