Cr, Co, Pd, Au, and In Overlayers on PbS(100) Surfaces: Adatom Interactions and Interface Formation

B.M.TRAFAS; I.M. VITOMIROV; C.M. ALDAO; Y. GAO; F. XU; J.H. WEAVER; D.L. PARTIN

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

APS

Año: 1989 vol. 39 p. 3265 - 3273

0163-1829

High-resolution synchrotron-radiation photoemission has been used to investigate Cr-, Co-, Pd-, Au-, and In-adatom depositions at room temperature on cleaved PbS(100) single-crystal surfaces. In general, these adatoms induce disruption of the substrate but the growth morphology and the distribution of the released Pb and S atoms in the overlayer varies a great deal. The deposition of adatoms of Cr, Co, Pd, and Au in small amounts leads to the appearance of a chemically shifted Pd Sd core-level component and at high coverage there is substantial Pb segregation to the free surface. Pb segregation is greatest for Cr and diminishes for Co, Pd, and Au. This ordering reflects difFerences in the amount of substrate disruption (greatest for Cr, least for Au) and the low solubility of Pb in these metals. The S 2p core-level results also reveal chemical changes associated with Crsulfide formation and the dissolution of S in, and on, the growing metal overlayer (surface segregation is greatest for Pd and Au and least for Cr). In contrast, studies of the In/PbS interface show that In forms clusters, that there is some disruption of the substrate, that S is expelled to the surface, and that Pb is released into the In overlayer.