The dielectric response functions in the valence bands and in the conduction band of heavily doped zincblende semiconductors have been evaluated using the self‐consistent field method and incorporating thefinitelifetime of particles in the relaxation time approximation. Scattering rates of injected electrons are calculated with the Born approximation in the dielectric response function formalism atfinitetemperature. The finite particle lifetime introduces significant modifications to the spectral density function {Im[−1/&egr;(q,&ohgr;)]} at smallq, where collective excitations (i.e., coupled phonon‐plasmon modes) are heavily damped due to collisions. However, these modifications are small at largeq. At the same time, the scattering rates of injected electrons are strongly affected by the temperature dependence of these effects, which are particularly significant forp‐type semiconductors.