Conduction properties of micro-crystals of 2,5-dimethyl-N,N′-dicyanoquinonediimine metal (metal = Ag, Cu) complexes on SiO2/Si substrates

Conduction properties of two kinds of DMe–DCNQI complexes deposited on SiO2/Si substrate are presented. Direct chemical growth of (DMe–DCNQI)2Ag on the substrate afforded single crystals attached to a gold electrode deposited on the substrate. The system showed bistable switching behavior associated with rectifying property, which seems suitable for resistive random access memory. Speculative mechanism for this behavior is discussed. On the other hand, single crystal of (DMe–DCNQI-d7)2Cu grown elsewhere was attached to four gold electrodes by carbon paste and fixed on the substrate with epoxy resin. Four-probe measurement of this sample revealed an absence of metal–insulator (M–I) transition which is expected at 80 K for crystal without substrate. This phenomenon can be explained by pseudo-negative pressure effect due to the hard silicon substrate (DMe–DCNQI = 2,5-dimethyl-N,N′-dicyanoquinonediimine).

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