Improved tunable InSb FIR detectors

We report about n-InSb tunable photoconductive detectors with a high resolution in the FIR region. The detection range can be tuned from 10 to 500 wavenumbers as a function of magnetic field. The limiting process of the signal to noise ratio in InSb detectors was found to be the recombination of electrons into surface states. By passivating these states the signal to noise ratio as well as the responsivity and the linewidth of InSb photoconductive detectors is improved considerably. The maxima in the responsivity and the signal to noise ratio can be shifted to lower energies and higher temperatures by using meander detectors.