Second-harmonic generation in GaAs:: Experiment versus theoretical predictions of χxyz(2) -: art. no. 036801

For GaAs we have determined \chi(xyz)((2))(-2omega; omega, omega)\ in second-harmonic generation experiments using two-photon energies between 2 and 5 eV. In addition to the E-1, E-1 + Delta(1), E-0', and E-2 critical-point bulk transitions of GaAs, a surprisingly strong surface transition at 3.35 eV was observed for natively oxidized GaAs(001) samples. A detailed comparison with theoretical predictions reveals that calculations that include many-particle effects at the level of the scissors approximation can describe the overall frequency dependence of the second-harmonic susceptibility reasonably well.