The exchange and correlation Exc of strongly correlated electrons in 2D
layers of finite width are studied as a function of the density parameter
rs, spin-polarization ζ and the temperature T. We explicitly treat
strong-correlation effects via pair-distribution functions, and introduce an
equivalent constant-density approximation (CDA) applicable to all the
inhomogeneous densities encountered here. The width w defined via the CDA
provides a length scale defining the z-extension of the quasi-2D layer
resident in the x-y plane. The correlation energy Ec of the quasi-2D
system is presented as an interpolation between a 1D gas of electron-rods (for
w/rs>1) coupled via a log(r) interaction, and a 3D Coulomb fluid closely
approximated from the known {\it three-dimensional} correlation energy when
w/rs is small. Results for the Exc(rs,ζ,T), the transition to a
spin-polarized phase, the effective mass m∗, the Land\'e g-factor etc.,
are reported here.Comment: Revtex manuscript, 9 postscript figure