OPTICAL ANISOTROPY OF ORDERED SB LAYERS ON III-V (110) SURFACES

Ordered Sb monolayers and multilayers on GaAs (110) and InP (110) have been studied in in situ by measuring the optical anisotropy (reflecta nce anisotropy spectroscopy) and the difference of the reflectivity wi th respect to the clean surface for linear polarized light (surface di fferential reflectance). The preparation was performed by annealing a 4-5 multilayer thick Sb film on ultrahigh vacuum-cleaved InP(110) and GaAs(110) substrates, which induces an ordered multilayer film of a me tastable crystal structure termed 'substrate-stabilized structure'. An nealing to higher temperatures can be utilized to prepare a highly ord ered monolayer film with a pseudomorphic lattice structure. Both monol ayers and multilayers have a geometrically anisotropic structure owing to the formation of Sb chains, which are derived either from the pseu domorphic growth or from the double-layer structure of the Sb crystal lattice, respectively. The substrate-stabilized multilayers show a str ong optical anisotropy of approximately 2-3% at 1.7 eV photon energy o n both InP and GaAs substrates which is related to the electronic stru cture of the multilayer. The ordered monolayers exhibit optical anisot ropies of comparable strength around 1.8 to 2.6 eV on GaAs(110) and 2. 0 to 2.7 eV on InP(110), which can be assigned to transitions between the electronic surface states.