Abstract

There is a lot of interest in developing nanoparticle-based electronic devices. These devices rely on single-electron charging effects and offer advantages in size and performance over traditional transistors. Two significant challenges to the development of nanoparticle electronics are to (a) arrange the particles into useful device structures and (b) characterize the structures of these arrays. We developed methods for arranging nanoparticies in one- and two-dimensional arrays, and have developed a new tool for characterization of nanostructures on SiO₂.

In order to characterize nanoparticle structures on SiO₂, we have designed substrates for TEM that are composed of a Si grid that supports electron transparent SiO₂ membrane windows. These grids are easily fabricated in large batches using standard microelectronic processing techniques and can be chemically processed in the same manner as a Si wafer.

Two-dimensional arrays of nanoparticles were patterned on SiO₂ using photolithography to pattern the oxide with a monolayer of Hf(IV), which is known to bind phosphoric acids. After removal of the photoresist, the chemically patterned surface is exposed to a solution of phosphoric acid-stabilized nanoparticles which selectively bind to the Hf(IV) patterned regions. EPMA analysis of the patterns shows that both Hf and Au are isolated within the patterned regions, and SEM images of these surfaces show that the particles form dense arrays on Hf(IV) modified Si. This assembly technique will allow facile integration of nanoparticle devices with current Si processing methods.

One-dimensional arrays of nanoparticles were assembled into device structures using DNA as a scaffold to direct the array. DNA is first aligned on SiO ₂, then the substrate is exposed to thiocholine-stabilized nanoparticles, which bind selectively to the DNA through electrostatic interactions. We have shown by TEM that nanoparticles deposited on DNA maintain their core size, and the interparticle spacing in these arrays is dictated by the length of the nanoparticle ligand shell. By controlling the surface chemistry of SiO ₂ and Au, we contacted isolated arrays of nanoparticles. These devices exhibit electrical properties consistent with theoretical treatments of nanoparticle arrays. "These advances will be useful in developing complex electronic circuits that take advantage of single-electron charging effects. This dissertation includes previously published co-authored material.