Optical second-harmonic generation study of barium deposition on Si(001)

Experimental results are presented on the deposition of barium on clean Si(001) studied by optical second-harmonic generation and work function measurements. Barium deposition up to one monolayer coverage enhances the signals by nearly a factor of 10. Continued deposition of Ba leaves the signal arising from the in-plane polarization component unaffected, indicating that this signal arises from the Si–Ba interface or the Ba–vacuum interface. In contrast, the second-harmonic signals related to the normal polarization components are increased by another order of magnitude around ∼4 ML Ba coverage.