Electronic and vibrational properties of ultrathin SiO_2 films grown on Mo(112)

摘要

Ultrathin SiO_2 films on Mo(112) were synthesized using different preparation procedures and characterized with ultraviolet photoelectron spectroscopy (UPS), metastable impact electron spectroscopy (MIES), and polarization modulation infrared reflection absorption spectroscopy (PM-IRAS). By correlating the vibrational and electronic data, an assignment of the prominent spectral features are made. The physical properties of SiO_2 films near one monolayer are influenced by the Mo substrate due to the Si-O-Mo linkages, whereas films greater than two monolayers show properties comparable to bulklike silica samples. The electronic and vibrational properties of the SiO_2 thin films are strongly coverage dependent. The data show that highly ordered SiO_2 films can be grown up to one monolayer, whereas films with a thickness of greater than one monolayer are amorphous.