  Out-of-plane screening (OPS) is expected to occur generally in
metal-semiconductor interfaces but this aspect has been overlooked in previous
studies. In this paper we study the effect of OPS in electron-hole bilayer
(EHBL) systems. The validity of the dipolar interaction induced by OPS is
justified with a RPA calculation. Effect of OPS in electron-hole liquid with
close-by screening layers is studied. We find that OPS affects the electronic
properties in low density and long wavelength regime. The corresponding
zero-temperature phase diagram is obtained within a mean field treatment. We
argue that our result is in general relevant to other heterostrucutures. The
case of strongly correlated EHBL is also discussed.
