Two-Color niBin Type II Superlattice Infrared Photodetector With External Quantum Efficiency Larger Than 100%

We report on a two-color niBin type II InAs/GaSb superlattice (SL) infrared photodetector. The two-color detection is realized by changing the applied bias polarity. At room temperature (RT), the 50% cutoff wavelength is 3.62 μm for one band and is 4.91 μm for the other at different bias voltage. The measured quantum efficiency (QE) of one band at the peak response is 114% at RT. This unusual QE is attributed to the large gain due to the photoconductive working mechanism. When temperature is raised from 90 to 300 K, the conduction of the SL absorber changes from pto n and thus the detector changes from photovoltaic to photoconductive when a bias voltage is applied.