Tunable Radiation Response in Hybrid Organic-Inorganic Gate Dielectrics for Low-Voltage Graphene Electronics.

Solution-processed semiconductor and dielectric materials are attractive for future lightweight, low-voltage, flexible electronics, but their response to ionizing radiation environments is not well understood. Here, we investigate the radiation response of graphene field-effect transistors employing multilayer, solution-processed zirconia self-assembled nanodielectrics (Zr-SANDs) with ZrOx as a control. Total ionizing dose (TID) testing is carried out in situ using a vacuum ultraviolet source to a total radiant exposure (RE) of 23.

Defect evolution in graphene upon electrochemical lithiation.

Despite rapidly growing interest in the application of graphene in lithium ion batteries, the interaction of the graphene with lithium ions and electrolyte species during electrochemical cycling is not fully understood. In this work, we use Raman spectroscopy in a model system of monolayer graphene transferred on a Si(111) substrate and density functional theory (DFT) to investigate defect formation as a function of lithiation. This model system enables the early stages of defect formation to be probed in a manner previously not possible with commonly used reduced graphene oxide or multilayer graphene substrates.

Influence of electronic type purity on the lithiation of single-walled carbon nanotubes.

Single-walled carbon nanotubes (SWCNTs) have emerged as one of the leading additives for high-capacity nanocomposite lithium ion battery electrodes due to their ability to improve electrode conductivity, current collection efficiency, and charge/discharge rate for high power applications. However, since as-grown SWCNTs possess a distribution of physical and electronic structures, it is of high interest to determine which subpopulations of SWCNTs possess the highest lithiation capacity and to develop processing methods that can enhance the lithiation capacity of underperforming SWCNT species. Toward this end, SWCNT electronic type purity is controlled via density gradient ultracentrifugation, enabling a systematic study of the lithiation of SWCNTs as a function of metal versus semiconducting content.

Topological transitions in carbon nanotube networks via nanoscale confinement.

Efforts aimed at large-scale integration of nanoelectronic devices that exploit the superior electronic and mechanical properties of single-walled carbon nanotubes (SWCNTs) remain limited by the difficulties associated with manipulation and packaging of individual SWNTs. Alternative approaches based on ultrathin carbon nanotube networks (CNNs) have enjoyed success of late with the realization of several scalable device applications. However, precise control over the network electronic transport is challenging due to (i) an often uncontrollable interplay between network coverage and its detailed topology and (ii) the inherent electrical heterogeneity of the constituent SWNTs.

Mechanism of very large scale assembly of SWNTs in template guided fluidic assembly process.

Very large scale patterned single-walled carbon nanotube (SWNT) networks were fabricated using a newly developed template guided fluidic assembly process. A mechanism for SWNT assembly and their control is described here. To maximize the directed assembly efficiency of SWNTs toward a wafer level SWNT deposition, Si or SiO(2) substrate was pretreated with precisely controlled SF(6), O(2), and Ar plasma.