Long-wavelength GaAs quantum-well IR detectors: low-temperature performance characteristics

We have fabricated and characterized several GaAs/AlGaAs multiquantum well infrared detectors at temperatures ranging from 6 K to 77 K. The detectors were designed to have a single bound state in the quantum well and the first excited state in the continuum above the AIGaAs conduction band edge. The difference in energy between the two levels, as determined by the quantum well width and aluminum mole fraction in the barrier, was chosen such that absorption would occur in the 8-14 tm wavelength region. Each detector was characterized by FTIR absorption, dark current, responsivity, spectral noise density, and thermal activation energy measurements. The -maximum observed detectivity is 1 .8 x 1 012 cmIHz/W at ?= 8.3 jim and 6 K.