Wafer-bonded Ge:Ga blocked-impurity-band far-infrared detectors

We report a successful fabrication of a far-infrared blocked-impurity-band (BIB) detector. We achieve a clear boundary interface between an absorption layer and a blocking layer with a transition layer of 8 nm thick by bonding two discrete germanium wafers using surface activated bonding (SAB) technique. As the results, a good responsivity of ~7 A/W at 2 K has been achieved with extended cutoff wavelength compared to a conventional Ge:Ga photoconductor detector.