Time-dependent heat diffusion in semiconductors by electrons and phonons

In this work the electron and phonon temperature distribution functions in semiconductors are calculated. We consider the time-dependent heat flux at the surface of the sample as a boundary condition for the electron and phonon systems, and a fixed temperature at the opposite surface. Those boundary conditions reflect the usual experimental setup in some photothermal experiments where the most common mechanism for producing interacting "thermal waves" is the absorption of an intensity-modulated light beam by the semiconductor. The electron and phonon temperature distributions in the sample are given as a function of both, time and position valid for a wide range of the modulation frequency omega of the incident light. The response of the system in the limit of high- and low-frequency omega with respect to the characteristic time tau(e)(tau(p)) of the electron (phonon) system is analyzed. [S0163-1829(98)08436-7].