  Restructuring of electronic spectrum in a buckled silicene monolayer under
some applied voltage between its two sublattices and in presence of certain
impurity atoms is considered. A special attention is given to formation of
localized impurity levels within the band gap and the to their collectivization
at finite impurity concentration. It is shown that a qualitative restructuring
of quasiparticle spectrum within the initial band gap and then specific
metal-insulator phase transitions are possible for such disordered system and
can be effectively controlled by variation of the electric field bias at given
impurity perturbation potential and concentration. Since these effects are
expected at low impurity concentrations but at not too low temperatures, they
can be promising for practical applications in nanoelectronics devices.
