Phonon band filling and photon emission by phonons

Phonon generation by electrons is studied in n-type Si crystals in electric fields E less than or equal to 100 kV/cm at the lattice temperature of 80 K employing the ensemble Monte Carlo technique. Electron transfer between e quivalent energy valleys is accounted for the g-type- and f-type phonon abs orption and emission. Acoustic phonons are accounted for the quasielastic s cattering of electrons within the energy valleys. Excess phonon number is d etermined using numerical data on phonon generation rate and experimental v alues of phonon lifetimes. The feasibility of stimulated emission of infrar ed-range photons due to direct optical transitions between the phonon bands is discussed.