COULOMB INTERACTION IN THE LAYERED ELECTRON-GAS

We discuss interplane attraction between electrons in the layered interacting two-dimensional electron gas. For small electron density, N2 < N2c (N2c is the critical density), anomalous many-body effects lead to an instability of the superlattice. It is found that in the regime of the instability the screened interplane electron-electron interaction potential is attractive. We suggest that for N2 < N2c the electron system breaks up into a confined Fermi liquid (electrons) and a gas of paired electrons (bosons). We calculate the density of bosons N2, as a function of the electron density and find N2B is-proportional-to N2/N2c[1 -(N2/N2c)1/2]. The specific heat and the importance of correlation effects are discussed.