Ultrafast electron dynamics at semiconductor surfaces and interfaces studied with subpicosecond laser photoemission.

The technique of subpicosecond angle-resolved laser photoemission spectroscopy is described. Investigations of the dynamics of electrons excited into normally unoccupied states at the cleaved GaAs (110) 1 x 1 and Ge (111) 2 x 1 surfaces are detailed. In addition, we discuss experiments carried out on heterostructures formed by the growth of Ge on the cleaved GaAs (110) surface as well as the molecular beam epitaxy (MBE) surfaces of GaAs (100) and (111).