Electron mobilities and photoelectron lifetimes in AlGaAs/GaAs and InGaAs/GaAs quantumhyphen;well infrared detectors

摘要

Gain and geometric magnetoresistance electron mobility measurements are presented for quantumhyphen;well infrared photoconductors. The electron mobility is found to be identical for both the photocurrent and the dark current and has a value of 2.6times;103cm2thinsp;Vminus;1thinsp;sminus;1in devices made from GaAs/AlxGa1minus;xAs and 9.4times;103cm2thinsp;Vminus;1thinsp;sminus;1in the InxGa1minus;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 AlxGa1minus;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 AlxGa1minus;xAs/GaAs detectors and 5.5 ps in the InxGa1minus;xAs/GaAs devices.