CNTs also offer new opportunities to study new science and develop new technology enabled by their strong electron-electron (e-e) interactions. The lack of dielectric screening inherent in nanoscale structures like CNTs leads to strong e-e interactions, which produce unique physical phenomena. In this thesis, we study the effects of strong...
PN junctions in nanoscale materials are of interest for a range of technologies including photodetectors, solar cells, and light-emitting diodes. However, Schottky barriers at the interface between metal contacts and the nanomaterial are often unavoidable. The effect of metal-semiconductor interfaces on the behavior of nanoscale diodes must be understood, both...
We study photocurrent generation in individual suspended carbon nanotube pn junctions using spectrally-resolved scanning photocurrent microscopy. Spatial maps of the photocurrent allow us to determine the length of the pn junction intrinsic region, as well as the role of the n-type Schottky barrier. We show that reverse-bias operation eliminates complications...
Ion pairs and solubility related to ion-pairing in water influence many processes in nature and in synthesis including efficient drug delivery, contaminant transport in the environment, and self-assembly of materials in water. Ion pairs are difficult to observe spectroscopically because they generally do not persist unless extreme solution conditions are...
Suspended metallic carbon nanotubes (m-CNTs) exhibit a remarkably large transport gap that can exceed 100 meV. Both experiment and theory suggest that strong electron-electron interactions play a crucial role in generating this electronic structure. To further understand this strongly-interacting system, we have performed electronic measurements of suspended m-CNTs with known...
Carbon nanotube (CNT) photodiodes have potential to convert light into electrical current with high efficiency. However, previous experiments have revealed photocurrent quantum yield (PCQY) well below 100%. In this work, we show that axial electric field increases the PCQY of CNT photodiodes. In optimal conditions our data suggest PCQY >...
In nanoscale materials, the Coulombic interaction between electrons are stronger than in bulk materials. These stronger interactions, caused by confinement and reduced dielectric screening, have interesting consequences for light-matter interactions. In carbon nanotubes (CNTs), strong interactions can enhance the impact ionization process, and thus assist photocurrent generation in CNTs. Conversely,...
Using a simple dry transfer process, I construct and characterize three nanoscale MoS2 devices using current-voltage curves, Raman spectroscopy, optical and atomic force microscopy. I compare these devices, the thinnest of which was few layer ( ≤ 10 nm) MoS₂ capable of showing photoconductance, with a current whose magnitude is...
Low-dimensional electronic materials offer a platform to observe biological processes with unprecedented spatial and temporal resolution. Carbon nanotubes (CNTs) are the closest physical analog to an ideal 1D system and can be scaled and integrated into multiplexed electronic circuitry. The molecular structure of a CNT is also biocompatible, making them...
Carbon Nanotubes are a unique family of nanostructures that have shown remarkable promise for mechanical, electrical, and optical applications. Fundamentally similar to the earlier discovered Buckminsterfullerene (C₆₀), carbon nanotubes are hollow cylinders formed from a single sheet of carbon atoms. The research presented in this dissertation investigates several carbon nanotube...
Carbon nanotube (CNT) photodiodes are a promising system for high-efficiency photocurrent generation due to the strong Coulomb interactions that can drive carrier multiplication. If the Coulomb interactions are too strong, however, exciton formation can hamper photocurrent generation. Here, we explore, experimentally and theoretically, the effect of the environmental dielectric constant...
Atomically-thin graphene sheets have unprecedented characteristics for biosensing applications. These characteristics include mechanical flexibility and strength, optical transparency, electrical sensitivity and biocompatibility. The primary theme of this dissertation is the characterization and application of graphene field-effect transistors (FETs) in biologically-relevant physiological environments.Understanding the interface that forms between an electrolyte and...
Recent interest in oxy-fuel combustion for carbon capture, as well as advancements in technologies such as magnetics, materials, and computational modeling has sparked renewed interest in magnetohydrodynamic (MHD) power generation. The increased temperatures of oxy-fuel combustion versus air-fuel combustion poses a challenge in the selection of materials for plasma exposed...
Monilinia vaccinii-corymbosi pseudosclerotia overwinter on the soil surface and produce apothecia in early spring, providing primary inoculum for Mummy Berry Disease of blueberry. Burial under 2.5 cm of soil or the absence of light have previously been identified as critical factors preventing the development of apothecia. Mulches were applied to...
Despite near unanimous opinion on the consequences of climate change by scientific community, the rate at which carbon is emitted into the atmosphere continues to increase. The need for a clean and sustainable source of energy is therefore one of humankind's most urgent challenges. Solar energy is the most abundant...