A new probe of metallization microstructure on semiconductor surfaces

Synchrotron radiation photoemission spectroscopy studies of the Xe 4d core level emission from Xe atoms physisorbed on unreactive Yb-GaAs(110) and reactive Yb-Hg_1-xCd_xTe(110) interfaces allowed us to detect the presence of metallic islands and follow the coverage-dependent evolution of island composition and morphology. Measurements of local island work function, and local work function of the semiconductor surface between the islands can be performed if the ionization energy of the adsorbed Xe atoms is known a priori. We conducted systematic studies of Xe physisorption on a variety of elemental metallic films and cleaved semiconductor substrates, and found that the 4d ionization energy of the first layer Xe atoms physisorbed on metals is relatively constant (65.7 ± 0.1 eV). On cleaved semiconductor surfaces the apparent 4d ionization energy for Xe atoms adsorbed in the first of two physisorption sites is also relatively constant, but 0.6 eV higher than that observed on metals.