A comparison of atomic layers formed by electrodeposition of selenium and tellurium - Scanning tunneling microscopy studies on au(100) and Au(111)

Structures formed by the electrodeposition of atomic layers of chalcogenide s Se and Te, on Au(100) and Au(111), are described and compared. Each eleme nt, on each surface, forms a low coverage structure, consisting of atoms pa cked simply in high coordinate sites at distances just above their van der Waals diameter. As coverages are increased above this level, structures com posed of chalcogenide atom chains or rings are formed. It is proposed that these chains or rings have significant molecular character, involving orbit al overlap of adjacent chalcogenide atoms. Mechanisms are described to acco unt for the formation of these chains and rings. Discussion is also present ed concerning the appearance of triangular phase boundaries for both chalco genides on Au(111). In the case of Se, isolated triangles, about 4-6 nm on a side are distributed across the surface, whereas a network of triangular phase boundaries is observed in the deposition of Te. The triangular phase boundaries in Se appear to result from the nucleation of domains in differe nt threefold sites on Au(111). For Te, however, it is proposed that the tri angular domains and phase boundaries are the result of Te atoms being too l arge to form an extended (root 3X root 3)R30 degrees structure. (C) 1999 Th e Electrochemical Society. S0013-4651(98)09-061-2. All rights reserved.