PHONON BROADENING OF IMPURITY SPECTRAL LINES: I. GENERAL THEORY

Abstract

The theory of the phonon broadening of impurity spectral lines is discussed within the framework of a Kubo-type formulation of the adiabatic dielectric susceptibility and the subsequent calculation of this using double-time Green's functions. The interaction of the bound electron (or hole) with the lattice vibrations is assumed to be weak and is treated as a small perturbation of the independent systems of electron and vibrating lattice; the use of the adiabatic approximation is thereby avoided. The cases in which the bound carrier states are degenerate and nondegenerate are discussed separately. The results are compared with previous work in the field.