The mid-infrared (mid-IR, 3-14 µm) spectral region is of significant importance for a wide range of applications, including spectroscopic analysis, free-space remote sensing, process monitoring, object detection and imaging, and potentially even free-space communication. Critical to many of these applications are infrared photodetectors, particularly those operating in one, or both, of two atmospheric transmission windows, the mid-wave infrared (MWIR, 3-5 µm) and the long-wave infrared (LWIR, 8-14 µm). Of these, the MWIR corresponds to the photon energies where objects with higher temperature emit thermal radiation, making the MWIR the preferred window for measuring reflected/emitted surface radiation in remote sensing applications, and for imaging/tracking phenomena such as forest fires, lava flows, and coal mine fires. Thus, MWIR photodetection is a vital component of any hyperspectral remote sensing system, essential for weather forecast models, climate science, and the measurement of water vapor in the atmosphere. There is thus great interest in equipping airborne and orbital satellite remote sensing systems with sensors covering a range of mid-IR wavelengths, almost always including the MWIR.
Our group has been developing semiconductor-based MWIR photodetectors operating at room temperature, with record low dark currents and strong external quantum efficiency by careful co-design of both electronic properties (i.e. bandstructure engineering) and photonic (i.e. plasmonic, leaky-cavity, and guided wave) enhancement.
In this presentation we will show recent advances in MWIR photodetector performance, including room-temperature operation of MWIR photodetectors with record-low dark currents compatible with focal plane array architectures, as well as work demonstrating new device designs capable of 4x or greater reduction in dark current without degradation of optical response. The presented detectors are well-suited for integration into sensing systems for Earth Science applications.