Electronic structure of CoSi(2) films on Si(111) studied using time-resolved two-photon photoemission.

The occupied and unoccupied electronic structure of thin epitaxial CoSi(2) films grown on Si(111) substrates was studied using time-resolved two-photon photoemission and valence-band photoemission spectroscopy. The work function of the sample surfaces and the Schottky barrier height at the metal-semiconductor interface were measured as a function of annealing temperature. The photoemission data reveal several occupied and unoccupied electronic states which exhibit a high sensitivity to the annealing temperature.

Time-resolved second-harmonic study of femtosecond laser-induced disordering of GaAs surfaces.

An abrupt (less than 100 fs) decrease in the second-harmonic intensity reflected from the surface of a GaAs (110) wafer has been observed experimentally. The linear reflectivity was found to increase on a time scale of ~1 ps. Thus the concept of fast atomic disorder induced by electronic excitation within a relatively cold lattice is given new experimental support.