Si/SiGe n-type inverted modulation doping using ion implantation

Inverted modulated-doped Si/Si1-xGex wafers have been prepared using ex-sit u ion implantation of a virtual substrate for the doping followed by cleani ng and the regrowth of the silicon quantum well in the growth system. This fabrication scheme attempts to circumvent the main problem in the growth of inverted modulation doped structures by chemical vapour deposition, which is the surface segregation and diffusion of n-type dopant causing high dopa nt densities in all subsequent layers after the introduction of n-type dopa nt to the growth chamber. Magneto-transport results will be shown for modul ation-doped field effect transistor (MODFET) samples which have 1.7 K mobil ities up to 73 000 cm(2)/V s for carrier concentrations of 4.25 x 10(11) cm (-2). Clear Shubnikov-de Haas oscillations and quantum Hall effect plateaux are visible demonstrating the quality of the samples produced using the te chnique. (C) 2000 Elsevier Science S.A. All rights reserved.