Selection rules are presented for intervalley scattering between the lowest conduction-band minima at $\Gamma$, $X$, and $L$ in the Brillouin zone of a III-V semiconductor. These selection rules are required for theories of the Gunn effect. The two most important crystals experimentally are GaAs, where longitudinal optic phonons cause the intervalley scattering, and InP, where longitudinal acoustic phonons produce the scattering.

• Received 6 October 1965

DOI:https://doi.org/10.1103/PhysRev.145.620