  We have analyzed various characteristic temperatures and energies of
hole-doped high-Tc cuprates as a function of a dimensionless hole-doping
concentration (pu). Entirely based on the experimental grounds we construct a
unified electronic phase diagram (UEPD), where three characteristic
temperatures (T*'s) and their corresponding energies (E*'s) converge as pu
increases in the underdoped regime. T*'s and E*'s merge together with the Tc
curve and 3.5kBTc curve at pu - 1.1 in the overdoped regime, respectively. They
finally go to zero at pu - 1.3. The UEPD follows an asymmetric half-dome-shaped
Tc curve in which Tc appears at pu - 0.4, reaches a maximum at pu - 1, and
rapidly goes to zero at pu - 1.3. The asymmetric half-dome-shaped Tc curve is
at odds with the well-known symmetric superconducting dome for La2-xSrxCuO4
(SrD-La214), in which two characteristic temperatures and energies converge as
pu increases and merge together at pu - 1.6, where Tc goes to zero. The UEPD
clearly shows that pseudogap phase precedes and coexists with high temperature
superconductivity in the underdoped and overdoped regimes, respectively. It is
also clearly seen that the upper limit of high-Tc cuprate physics ends at a
hole concentration that equals to 1.3 times the optimal doping concentration
for almost all high-Tc cuprate materials, and 1.6 times the optimal doping
concentration for the SrD-La214. Our analysis strongly suggests that pseudogap
is a precursor of high-Tc superconductivity, the observed quantum critical
point inside the superconducting dome may be related to the end point of UEPD,
and the normal state of the underdoped and overdoped high temperature
superconductors cannot be regarded as a conventional Fermi liquid phase.
