Boltzmann-Equation Study of Hot-Electron Relaxation in Metals

The relaxation of a hot-electron distribution, in strong interaction with a dense cold-electron gas, is studied using a time-dependent Boltzmann-equation approximation. In the approximation which drops a collision recovery term, the theory becomes equivalent to Quinn's self-energy approach. Assuming the distribution function to be isotropic in momentum space for all times, the Boltzmann equation is integrated to give the time development of an initially sharply peaked distribution. Attention is focused on the shape of the distribution as it relaxes, and the effect of the spreading of the distribution on the rate of energy loss is analyzed. In the final section of the paper, the results are discussed with relation to certain models of hot-electron transport in thin-film structures.