We extend our previously suggested drift-diffusion (DD)-based hot-carrier degradation model to the case of decananometer transistors. Special attention is paid to the effect of electron-electron scattering, which populates the high energy tail of the carrier distribution function, by using a rate balance equation. We compare the results of the DD-based model with the results obtained from a spherical harmonics expansion of the Boltzmann transport equation as well as experimental data. We also study the accuracy and limits of the applicability of the DD-based model and conclude that this model is able to capture hot-carrier degradation in nMOSFETs over a range of gate lengths from 65 to 300 nm with excellent accuracy.