  We present an InAs-GaSb-based system in which the electric-field tunability
of its 2D energy gap implies a transition towards a thermodynamically stable
excitonic condensed phase. Detailed calculations show a 3 meV BCS-like gap
appearing in a second-order phase transition with electric field. We find this
transition to be very sharp, solely due to exchange interaction, and so, the
exciton binding energy is greatly renormalized even at small condensate
densities. This density gradually increases with external field, thus enabling
the direct probe of the Bose-Einstein to BCS crossover.
