Effects of finite layer thickness on the differential capacitance of electron bilayers

We have calculated the effects of the finite thickness of electron or hole layers in double-quantum-well systems on the complete set of differential capacitances that can be measured in double-layer electron systems, with or without separately contactable layers.~ We~present results for~the regime of negligible interlayer tunneling, zero applied magnetic field, and low layer densities, when the compressibility of~one or~both layers is negative.