Abstract
The dielectric response of an electron-hole plasma confined to a slab is calculated within the Hartree approximation for electric fields perpendicular to the slab walls. The results are used to infer the capacitance behavior of photoexcited quantum-well structures under different rate conditions. Case studies show that nonlinearities in the carrier-density dependence of the energy spectrum and scattering times can lead to bistability and negative differential capacitance.