Electronic structure and electron dynamics at the GaSb(0 0 1) surface studied by femtosecond pump-and-probe pulsed laser photoemission spectroscopy

Transiently excited electron states at the GaSb(0 0 1) surface have been studied by means of time- and angle-resolved photoemission spectroscopy based on a femtosecond laser system. A normally unpopulated surface electron state has been found at 250 meVabove the valence band maximum with a strong confinement at the center of the surface Brillouin zone. The lifetime of transiently excited carriers at the intergap surface states has been found to be 11 ps, associated with rapid carrier diffusion.