  We have used a field-penetration method to measure thermodynamic
compressibility of a moderately interacting two-dimensional electron system
($r_{s}$ $\approx$ 0.5-3) in a three terminal GaAs/AlGaAs device, fabricated
with an epitaxial lift-off technique. We found that the density and temperature
dependencies of the compressibility are qualitatively different from that
observed in earlier studies of the 2D hole system, where interaction energies
are considerably stronger. We show that the observed characteristics can be
described by the recently developed formalism for compressibility of the
droplet state.
