We present measurements of Coulomb drag in an ambipolar GaAs/AlGaAs double
quantum well structure that can be configured as both an electron-hole bilayer
and a hole-hole bilayer, with an insulating barrier of only 10 nm between the
two quantum wells. The Coulomb drag resistivity is a direct measure of the
strength of the interlayer particle-particle interactions. We explore the
strongly interacting regime of low carrier densities (2D interaction parameter
rs up to 14). Our ambipolar device design allows comparison between the
effects of the attractive electron-hole and repulsive hole-hole interactions,
and also shows the effects of the different effective masses of electrons and
holes in GaAs.This work was financially supported by the UK Engineering and Physical Sciences Research Council. A.F.C. acknowledges financial support from Trinity College, Cambridge, and IF from Toshiba Research Europe.This is the author accepted manuscript. The final version is available from the American Institute of Physics via http://dx.doi.org/10.1063/1.494176
