Voltage tunable superlattice infrared detector for mid- and long-wavelength detection

Abstract

We have designed and fabricated a voltage tunable superlattice (SL) infrared photodetector where the detection wavelength switches from the 3–5μm midwavelength infrared (MWIR) range under negative bias to the 8–12μm long-wavelength infrared (LWIR) range under large positive bias. The structure consists of multiple periods of two different SLs that are separated by undoped blocking barriers on one side and heavily doped layers on the other side. The background-limited temperature with F∕1.2 optics is 110 and 70 K for mid- and long-wavelength detection, respectively. This voltage tunable MWIR/LWIR detector has a performance comparable to those of one-color quantum-well infrared detectors designed for the respective wavelength ranges.