Carrier distribution in quantum nanostructures by scanning capacitance microscopy

Scanning capacitance microscopy (SCM) was carried out in the angle beveling configuration on B doped, very narrow quantum wells (QWs) of Si0.75Ge0.25 layers strained between Si films. The majority carrier concentration profiles were calculated from the SCM raw data measured on QWs with a minimum width of 5 nm, doped with different B concentrations ranging from 2x10(16) to 6x10(18) cm(-3). The equilibrium carrier distribution in the heterostructures has been calculated by different simulation approaches, which will be discussed. Moreover, the effect of the biased tip-sample interaction was studied by accurate simulations of the dC/dV vs V characteristics for different positions of the tip moving on the beveled sample surface. The agreement between the experimental and simulated SCM profiles is very good. Thus, a spatial SCM resolution of at least 5 nm was demonstrated on angle beveled samples, not only in terms of signal sensitivity, but also in terms of quantitative majority carrier profiling.