Modeling of parasitic barrier effects in silicide/Si1−xGex Schottky-barrier infrared detectors fabricated with a silicon sacrificial layer

Abstract

By employing a thin silicon sacrificial cap layer for silicide formation, we have fabricated both Pd2Si/Si1−xGex and PtSi/Si1−xGex Schottky-barrier infrared detectors with extended cutoff wavelengths and near-ideal leakage characteristics. Substantial deviation in the spectral response from Fowler’s theory was observed in some silicide/Si1−xGex detectors fabricated using this technique. This deviation was attributed to a parasitic barrier at the interface due to the excess silicon sacrificial layer left unconsumed by the silicide formation process. A simple model which modifies Fowler’s theory to take into account the reduced injection efficiencies of the photoexcited holes through the Si barrier was proposed. Good agreement between this model and the experimental data has been achieved.