Electrically-tunable infrared detectors based on intraband transitions in quantum well structures

This work describes the design and construction of electrically-tunable infrared detectors for the mid-infrared, (3-25 microns), based on photon-assisted resonant tunneling in the AlGaAs/GaAs system. Conventional approaches to detector design involve the choice of an intuitive quantum structure, which is then optimized for the purpose. Instead, we choose to exploit the full range of quantum structures that can be grown using molecular beam epitaxy (MBE) by applying systematic search techniques. To do this, we first parameterize the space of MBE structures. We then develop models of relevant detector characteristics and define a measure of the structures' relative suitability based on those characteristics. A rapid quantum-structure modeling procedure is developed to realize this search in reasonable time. Promising structures are fabricated and the results compared with related tunable detector approaches. A tunable detector centered at 7...