Heating of cold electrons by a warm GaAs lattice: A novel probe of the carrier-phonon interaction

Cooling of an electron-hole plasma after picosecond photoexcitation strongly decreases at carrier densities exceeding 1×${10}^{17}$ ${\mathrm{cm}}^{\mathrm{-}3}$. In contrast, the reverse process of heating a cool electron-hole plasma via phonon absorption from the warm lattice is independent of carrier density up to 4×${10}^{17}$ ${\mathrm{cm}}^{\mathrm{-}3}$, establishing the first experimental evidence for negligible screening of the Fröhlich interaction.