Semiconductor anisotropic properties

Single crystals are essential in some cases or to study anisotropic properties fields as semiconductors and optics require large-size, highly pure, defect-free. 

While complexes in which the metal is coordinatively unsaturated frequently oligomerize utilizing bridging jS-diketonate ligands, a different mode of aggregation is believed to occur in M(CO)2-(MeCOCHCOMe) (M = Rh, Ir), The near planarity of the acetylacetonate permits these flat molecules to stack so that short (3.20 A for Ir) metal-metal contacts are formed. This leads to highly anisotropic DC electrical transport properties and these compounds are semiconductors. 

The crystal structure and electrical conduction properties of (Et4N)0,5[Ni(dmit)23 (where dmit = isotriethione dithioiate) have been reported.120 In the crystal, face-to-face stacking and side-by-side arrangement of Ni(dmit)2 molecules form a two-dimensional S—S network. The compound is an anisotropic semiconductor with a maximum conductivity of 4.5 x 10-2 Q"1 cm 1 in the stack direction.120... 

Metal-chain complexes containing stacked square-planar tetracyanoplatinate groups, [Pt(CN)4]2", are currently of high interest because of their one-dimensional (very anisotropic ) metallic properties. Complexes of this type contain metal-atom chains and often possess a characteristic brilliant, metallic luster. They may be synthesized by oxidation using chemical or electrolytic techniques.1 Although these compounds often appear metallic, they may also be semiconductors. These complexes differ in their Pt-Pt intrachain separations, degree of partial oxidation of the platinum atom (Pt2-1 2 4), electrical conductivity, and metallic color.2 Compounds in this series which contain platinum atoms in a nonintegral oxidation state are known as partially oxidized tetra-cyanoplatinate (POTCP) complexes. Some complexes also possess a metallic luster but are not metallic, as is the case for Tl4(C03)[Pt(CN)4] (see below). 

Electrical conductivity and thermopower measurements on single crystals of t(NHs) tCk (MGS) and (TTF) NiS C H (TTF = tetrathiafulvalene) illustrate the application of electrical property measurements to the study of intermolecular interactions and electronic structure in planar metal complex systems. MGS is an anisotropic, p-type semiconductor conductivity along the metal-chain direction ohm ... 

In addition to systems with one-dimensional metallic properties, there are a considerably larger number of planar metal complexes where stacking interactions in the solid state give rise to unusual properties including highly anisotropic conductivity behavior but where electronic or structural factors lead to thermally activated conductivities 10, 11), Such one-dimensional semiconductors constitute an important area of study within the general topic of solids with one-dimensional interactions, and their study has provided much useful information regarding structure-property relationships. 

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