  Exciton Mott physics in two-dimensional electron-hole (e-h) systems is
studied in the quasiequilibrium, which is the crossovers or phase transitions
between the insulating exciton gas and the metallic e-h plasma. By developing a
self-consistent screened T-matrix approximation, we succeed in obtaining the
"global" phase diagram on the plane of the e-h density and the temperature as a
contour plot of the exciton ionization ratio. The detailed features of the
exciton-Mott crossover at high temperature are figured out beyond the
conventionally used concept of the Mott density. At low temperature, we find
not only the region unstable toward the inhomogeneity but the pure Mott
transition point characterized by the discontinuity in the ionization ratio.
The single particle spectra also exhibit interesting features reflecting the
excitonic correlations.
