Si/SiGe MODFETs
SiGe Modulation-Doped FETs
Modulation-doped silicon quantum wells have demonstrated the highest mobility of any silicon devices. Room temperature mobilities up to 2,400 cm2/Vs and low temperature mobilities up to 390,000 cm2/Vs at low temperature. The diagram on the right shows the layer structure and bands.
Low temperature measurements allow the mobility limiting scattering mechanisms to be determined. Fractional quantum Hall states (see left) are only observed in the highest quality and mobility material.
On the right is a comparison of a number of different low temperature mobilities as a function of carrier density. The two lines correspond to background limited mobility as calculated by Steven Laux.
Significant publications:
A.C. Churchill, D.J. Robbins, D.J. Wallis, N. Griffin, D.J. Paul and A.J. Pidduck “High mobility two dimensional electron gases in Si/SiGe heterostructures on relaxed SiGe layers grown at high temperature” Semiconductor Science and Technology 12, pp943-945 (1997)
D.J. Paul, A. Ahmed, N. Griffin, M. Pepper, A.C. Churchill, D.J. Robbins and D J Wallis “Electrical properties of two dimensional electron gases grown on cleaned SiGe virtual substrates” Thin Solid Films 321, pp181-185 (1998)
A. Ahmed, R.B. Dunford, D.J. Paul, M. Pepper, A.C. Churchill, D.J. Robbins and W.Y. Leong “Si/SiGe n-type inverted modulation-doping using ion implantation” Thin Solid Films 369, pp324-327 (2000)
