Long-Wavelength Phonon Scattering in Nonpolar Semiconductors

The long-wavelength acoustic- and optical-phonon scattering of carriers in nonpolar semiconductors is considered from a general point of view. The deformation-potential approximation is defined and it is shown that long-range electrostatic forces give a nontrivial correction to the scattering. For completeness, corrections due to nonlocal effects like spin-orbit coupling are treated, but the general conclusion is that the deformation-potential approach is a very good approximation except in some cases of optical-phonon scattering. The smallness of the nontrivial corrections is interpreted in terms of the very-short-range nature of interactions in a covalent semiconductor.