Electron-phonon interactions which involved semiconductor surface states were studied via the temperature dependence of their photo-emission line-widths. Measurements of the anion-derived dangling-bond and bridge-bond surface states at critical points of (110) cleaved surfaces were performed at temperatures of between 90 and 500K by using high-resolution angle-resolved photo-emission spectroscopy. The values of the line-width which were determined for 0K lay between 0.246 and 0.416eV and were much larger than those found for metal surfaces. In addition to the intrinsic lifetime, there appeared to be a contribution (to the surface-state line-width) which arose from surface defects such as steps. The latter were always present to some extent on cleaved surfaces. The localized nature of semiconductor surface states made them very sensitive to such defects. The temperature coefficients lay between 0.18 and 0.38meV/K for the dangling-bond surface states and between 0.07 and 0.13meV/K for the bridge-bond surface states. The possible effect of plasmon interactions was also considered by studying highly doped GaAs samples.

J.Fraxedas, M.K.Kelly, M.Cardona: Physical Review B, 1991, 43[3], 2159-8