LOW SCHOTTKY-BARRIER JUNCTIONS ON STRAINED P-SI1-XGEX FOR INFRARED DETECTION

Electrical properties of different low Schottky barrier junctions on h igh quality strained-Si1-xGex layers with 0 less than or equal to x le ss than or equal to 0.24 were studied. The investigated metals were Ir , Pt, Pd and Fe. In addition, PtSi/p-Si1-xGex junctions were also prod uced and characterized; the silicide was deposited by co-sputtering. H igh-resolution multi-crystal x-ray diffraction (HR-MCXRD) was used to investigate the sample quality and strain state of the MBE grown p-Si1 -xGex layers and to accurately determine the Ge fraction in the fabric ated junctions. The Schottky barrier height of the studied junctions w ere found to decrease with the Ge fraction (x) in the Si1-xGex layer. Different junctions showed the same dependence on the Ge fraction. The reduction of the barrier heights with increasing Ge fraction was foun d to be related to the valence band discontinuity in the underlying Si 1-xGex/Si heterojunction. It was then concluded that the cut-off wavel ength of infrared detector fabricated on Si1-xGex layer can be tuned i n a wide range in the infrared region by changing x. A cut-off wavelen gth of 13.8 mu M was shown to be feasible in this work.