  Ultra-scaled FinFET transistors bear unique fingerprint-like device-to-device
differences attributed to random single impurities. This paper describes how,
through correlation of experimental data with multimillion atom tight-binding
simulations using the NEMO 3-D code, it is possible to identify the impurity's
chemical species and determine their concentration, local electric field and
depth below the Si/SiO$_{\mathrm{2}}$ interface. The ability to model the
excited states rather than just the ground state is the critical component of
the analysis and allows the demonstration of a new approach to atomistic
impurity metrology.
