Highly oriented pyrolytic graphite HOPG metals

An STM probe has been used to isolate individual MS (M = Cd, Pb) particles and to measure electronic phenomena (55,56,81). The MS films were prepared either by exposure of metal ion/fatty acid films to H2S (55,56) or by transfer of a compressed DDAB-complexed CdS monolayer (81). All the films were transferred onto highly oriented pyrolytic graphite (HOPG) for the STM measurements. A junction was created at an individual CdS particle with the STM tip as one electrode and the graphite as the other, and the current/voltage characteristics of the panicles were measured. For the particle prepared in the fatty acid films the I/V curves exhibit step-like features characteristic of monoelectron phenomena. In the case of the DDAB-coated CdS particles the I/V measurements demonstrated n-type semiconductor behavior. The absence of steps in this system is probably a reflection of the larger size of the particles in the DDAB films (8 nm by AFM) compared to the 2-nm particle size typically found for MS particles formed in fatty acid films. 

Clusters of various metals can be formed by use of a dewetting (Vollmer-Weber) type of epitaxial growth this has been done mainly on highly oriented pyrolytic graphite (HOPG). Eormation of 3-D islands has been reported for Cu, Ag, Au [3.134], Pt [3.135], Co [3.136], Mo, [3.137], and Pd [3.138]. 

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