The attempt to describe the bell-shape dependence of the critical temperature
of high-Tc superconductors on charge carriers density is made. Its linear
increase in the region of small densities (underdoped regime) is proposed to
explain by the role of the order parameter phase 2D fluctuations which become
less at this density growth. The critical temperature suppression in the region
of large carrier densities (overdoped regime) is connected with the appearance
(because of doping) of the essential damping of long-wave bosons which in the
frame of the model proposed define the mechanism of indirect inter-fermion
attraction.Comment: 15 pages, 3 figures, EMTE