CHARGE-TRANSPORT IN STRAINED SI1-YCY AND SI1-X-YGEXCY ALLOYS ON SI(001)

We have investigated the temperature dependencies of charge carrier de nsities and Hall mobilities in tensile strained Si1-yCy and in compres sively strained Si1-x-yGexCy layers. In both cases, the measured charg e carrier densities at room temperature are not affected substantially by the addition of a small concentration of carbon (<1%) under identi cal growth conditions and dopant fluxes. The measured Hall mobilities monotonically decrease with increasing carbon content for electrons in Si1-yCy, and for holes in Si1-x-yGexCy, respectively. Our results ind icate that electrically active defects are formed with the addition of carbon. These defects are presumably connected with carbon/Si interst itials or other C-related complexes. It seems to be difficult to attri bute the formation of those electrically active defects solely to cont aminations originating from the used carbon evaporation source. We obs erved that donor-and acceptor-like defects are formed in Si1-yCy as we ll as in Si1-x-yGexCy layers with roughly a constant ratio, independen t of source temperature. (C) 1997 American Institute of Physics.