ABSTRACT NA, JEONG-SEOK. Nanoscale Assembly for Molecular Electronics and In Situ Characterization during Atomic Layer Deposition. (Under the direction of Dr. Gregory N. Parsons.) The work in this dissertation consists of a two-part study concerning molecular-based electronics and atomic layer deposition (ALD). As conventional “top-down” silicon-based technology approaches its expected physical and technical limits, researchers have paid considerable attention to “bottom-up” approaches including molecular-based electronics that self assembles molecular components and ALD techniques that deposit thin films with atomic layer control. Reliable fabrication of molecular-based devices and a lack of understanding of the conduction mechanisms through individual molecules still remain critical issues in molecular-based electronics. Nanoparticle/molecule(s)/nanoparticle assemblies of “dimers” and “trimers”, consisting of two and three nanoparticles bridged by oligomeric ethynylene phenylene molecules (OPEs), respectively, are successfully synthesized by coworkers and applied to contact nanogap electrodes (< 70 nm) fabricated by an angled metal evaporation technique. We demonstrate successful trapping of nanoparticle dimers across nanogap electrodes by dielectrophoresis at 2 VAC, 1 MHz, and 60 s. The structures can be maintained electrically connected for long periods of time, enabling time- and temperature-dependent current−voltage (I−V) characterization. Conduction mechanisms through independent molecules are investigated by temperature dependent I−V measurements. An Arrhenius plot of log (I) versus 1/T exhibits a change of slope at ~1.5 V, indicating the transition from direct tunneling to Fowler−Nordheim tunneling. Monitoring of the conductance is also performed in real-time during trapping as well as during other modification and exposure sequences