Photoemission study of Sm/CdTe interface formation

Synchrotron radiation photoemission has been used to study the formation of Sm overlayer on the surface of CdTe(1 0 0) crystal. The data were recorded at room temperature for Sm coverage ranging from 0 to 9 ML. The analysis of constant initial state spectra and energy distribution curves taken in the valence band region showed that at very low Sm coverage (0.1 and 0.2 ML) the trivalent Sm state dominates. For higher coverages the average valence of the system drops down from the value of 2.7 to 2.2 for 1.8 ML. The analyses of Sm4f multiplet peaks binding energy lead to the conclusion that the average valence of Sm in the Sm/CdTe(1 0 0) system is heterogeneous (the valence has site-dependent but integer value). The photoemission results indicate strong Sm–CdTe interaction and confirm the assumption about the creation of a surface compound with spinel CdSm2Te4 structure.