Interaction of hot carriers with optical phonons in Selenium

An interaction of hot charge carriers with optical phonons in Selenium is studied theoretically from first principles. The results suggest that the electron–phonon matrix element for energetic electrons is significantly greater than that for holes. This effect is attributed to the weak coupling of lone-pair states to lattice perturbations associated with optical vibrational modes. Hence, the energy relaxation time due to the emission of optical phonons for holes is expected to be longer than that for electrons. The longer relaxation time favors the impact ionization of holes.