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We have investigated the selective electroless deposition (ELD) of Cu on functionalized self-assembled monolayers (SAMs). Previous studies have demonstrated that Cu deposits on −COOH and −CH3terminated SAMs using ELD. However, the deposited films were rough and contained irregular crystallites. Further, the copper penetrated through the film. In this Article, we demonstrate that copper can be selectively deposited on −COOH terminated SAMs with improved morphology and without penetration of copper through the organic layer. The method employs a Cu(II) seed layer and an additive, adenine or guanine. We demonstrate the efficacy of the technique on photopatterned −CH3/–COOH SAMs. Copper is observed to deposit only atop the −COOH terminated SAM area and not on the −CH3terminated SAM. The use of a Cu(II) seed layer increased the Cu ELD rate on both −COOH and −CH3terminated SAMs. The deposited copper layer strongly adheres to the −COOH terminated SAMs because the copper layer nucleates at Cu2–carboxylate complexes. In contrast, the deposited copper layer can easily be removed from the −CH3terminated SAM surface because there is no specific copper–surface interaction. The additives adenine and guanine mediate the interaction of Cu2橷 the deprotonated −COOH terminated SAMs via the formation of additive–carboxylate complexes. These complexes lead to significantly reduced copper penetration through the SAM. In the case of adenine, the diffusion of copper through the organic film was eliminated. This new technique for copper deposition will facilitate the development of inexpensive molecular electronics, sensors, and other nanotechological devices. [ABSTRACT FROM AUTHOR]

Electroless nanowire deposition on micropatterned substrates (ENDOM) is a promising new technique by which to direct the synthesis and precise placement of metallic nanowires. ENDOM is generally applicable to the preparation of metallic, semiconducting, and even insulating nanowires on technologically relevant substrates, is inexpensive, and can achieve high growth rates. The deposited nanowires are ultralong (centimeters) and can be patterned in arbitrary shapes. We demonstrate ENDOM using the growth of nickel nanowires. By controlling the deposition time, the width of the nanowires can be varied from 200 to 1000 nm and the height can be varied from 7 to 20 nm. [ABSTRACT FROM AUTHOR]

We have investigated the seedless electroless deposition (ELD) of Ni on functionalized self-assembled monolayers (SAMs) using scanning electron and optical microscopies, X-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry. For all SAMs studied, the Ni deposition rate is dependent on the bath pH, deposition temperature, and complexing agent. In contrast to the physical vapor deposition of Ni on SAMs, electrolessly deposited Ni does not penetrate through the SAM. This behavior indicates that ELD is a suitable technique for the deposition of low-to-moderate reactivity on organic thin films. We demonstrate that Ni can be selectively deposited on SAMs using two different methods. First, selectivity can be imparted by the formation of Ni(II)–surface complexes. As a demonstration, we selectively deposited Ni on the −COOH terminated SAM areas of patterned −COOH/–CH3or −COOH/–OH terminated SAMs. Here, Ni2+ions form Ni2+–carboxylate complexes with the −COOH terminal group, which comprise the nucleation sites for subsequent metal deposition. Second, we demonstrate that nickel is selectively deposited on the −CH3terminated SAM areas of a patterned −OH/–CH3terminated SAM. In this case, the Ni2+ion does not specifically interact with the −CH3terminal group. Rather, selectivity is imparted by the interaction of the reductant, dimethylamine borane (DMAB), with the −OH and −CH3terminal groups. [ABSTRACT FROM AUTHOR]