Low Schottky barrier junctions on strained p-Si1-xGex for infrared detection

Nur, O
Willander, M
Turan, Raşit
Sardela, MR
Hansson, GV
Electrical properties of different low Schottky barrier junctions on high quality strained-Si1-xGex layers with 0 less than or equal to x less 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 produced and characterized; the silicide was deposited by co-sputtering. High-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 fabricated junctions. The Schottky barrier height of the studied junctions were 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 found to be related to the valence band discontinuity in the underlying Si1-xGex/Si heterojunction. It was then concluded that the cut-off wavelength of infrared detector fabricated on Si1-xGex layer can be tuned in a wide range in the infrared region by changing x. A cut-off wavelength of 13.8 mu M was shown to be feasible in this work.