  The influence of an impurity atom on the electrostatic behaviour of a Single
Molecular Transistor (SMT) was investigated through Ab-initio calculations in a
double-gated geometry. The charge stability diagram carries unique signature of
the position of the impurity atom in such devices which together with the
charging energy of the molecule could be utilised as an electronic fingerprint
for the detection of such impurity states in a nano-electronic device. The two
gated geometry allows additional control over the electrostatics as can be seen
from the total energy surfaces (for a specific charge state) which is sensitive
to the positions of the impurity. These devices which are operational at room
temperature can provide significant advantages over the conventional Silicon
based single dopant devices functional at low temperature. The present approach
could be a very powerful tool for the detection and control of individual
impurity atoms in a single molecular device and for applications in future
molecular electronics.
