The local electroneutrality manifestation in defective bulk semiconduc
tors - electron (hole) chemical potential (Fermi-level) pinning near t
he local neutrality level (LNL)- is researched experimentally in heavy
irradiated crystals. A novel equation for the determination of the LN
L-energy (E(LNL)) in semiconductors has been obtained from the princip
les of quantum statistical physics of the solid state. The numerical c
alculations of E(LNL) are fulfilled for a large group of semiconductor
s. A striking correlation between experiment and theory is revealed.