Electron mobilities and photoelectron lifetimes in AlGaAs/GaAs and InGaAs/GaAs quantum-well infrared detectors

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Abstract
Gain and geometric magnetoresistance electron mobility measurements are presented for quantum‐well infrared photoconductors. The electron mobility is found to be identical for both the photocurrent and the dark current and has a value of 2.6×103 cm2 V−1 s−1 in devices made from GaAs/AlxGa1−xAs and 9.4×103 cm2 V−1 s−1 in the InxGa1−xAs/GaAs devices at 77 K. This difference in mobility is associated with the purity of the barrier material which is much greater in GaAs than in AlxGa1−xAs. The photoelectron lifetime before recapture can be deduced from the combination of the gain and mobility measurements. This lifetime is found to be 7.2 ps in the AlxGa1−xAs/GaAs detectors and 5.5 ps in the InxGa1−xAs/GaAs devices.