Drift mobility in quantum nanostructures by scanning probe microscopy

We used scanning capacitance microscopy (SCM) and scanning spreading resistance microscopy (SSRM) to determine the drift hole mobility in nanometer thick Si/Si0.75Ge0.25/Si quantum wells (QWs), from the carrier concentration profiles (obtained by SCM) and the local resistivity values (obtained by SSRM). A relevant decrease of the hole mobility at room temperature was observed when reducing the QW width from 10 nm down to 1 nm. This effect has been explained in terms of the increasing role of surface scattering at the Si/SiGe interface for lower QW widths.