Interband response of type-II quantum cascade detectors [Invited]

Quantum cascade detectors (QCDs) are room-temperature photovoltaic infrared devices based on intersubband transitions. In this work, we expand the mid-infrared QCD functionality by utilizing the interband (IB) transitions in the extractor region to realize a detector also in the short-wavelength infrared region of the electromagnetic spectrum. We investigate this scheme with simulations and characterization of the IB transitions in type-II InAs/AlSb QCD structures on GaSb substrates. We compare four different QCD devices with IB transitions between 1.83 µm and 2.33 µm. The measured peak responsivities at zero bias are 2.8 – 24.8 mA W¯¹ with specific detectivities between 2.56×10⁷ – 1.68×10⁸ Jones. A detailed analysis of the devices under an applied bias shows that the IB response increases up to 330 times at a bias of 1.0 V and 360 times at a bias of -1.0 V.