Direct experimental verification of the q-dependence of the electron–LO-phonon interaction

Hot electron luminescence from p-doped semiconductor quantum wells is partly polarised because of the optical selection rules involved. For linearly polarised excitation, the photoelectrons have an anisotropic distribution in k-space which determines the polarisation of the resulting luminescence. LO-phonon scattering degrades the angular structure in the distribution, reducing the degree of polarisation. Measurements of this depolarisation for electrons excited in specific k-directions are compared with calculations for various q-dependences of the electron–LO-phonon interaction, demonstrating the validity of the accepted Fröhlich 1/q2 dependence.